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This Biologist Panned a “Mosquito Eradicator” Product. Its Maker Bit Back.

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Sunday, June 16, 2024

In 2019, Colin Purrington, an evolutionary biologist, was scrolling through the internet when he came across something that would change his life. Purrington, 57, who left a professor position at Swarthmore College in 2011 to spend more time with his family, dabbles these days: He snaps nature photography, gives presentations at the local farmer’s market, and occasionally reviews products for his personal blog. On that fateful day in 2019, a new product had caught his eye: The Spartan Mosquito Eradicator, a roughly foot-long black and orange tube with a Corinthian helmet emblazoned on the side, its plumes replaced by mosquito wings. Inside was a mixture of sugar, yeast, and salt. “I was intrigued, given that it said that it could kill 95 percent of mosquitoes,” Purrington recalled in an interview with Undark. The claims seemed too good to be true, he thought, so he decided to try it out. After purchasing two tubes for about $25, Purrington hung them in his yard in Pennsylvania and checked them, he says, more than a 100 times over the summer. But he didn’t see much happen, a fact that compelled him to write a nearly 4,000-word review on his personal website. To say it was a pan is an understatement. “The Spartan Mosquito Eradicator is unlikely to kill a single mosquito unless it falls from the tree and lands on one,” Purrington wrote. He called some of the company’s claims “idiotic.” He also laid out a lengthy case that the company had misled regulators about the efficacy of its product, lied to customers, and broken some laws—and encouraged readers to contact regulators and file complaints. “My attorneys were the same ones that sued Rolling Stone and won, so they are pretty good at that.” A tube of baking ingredients might not seem like much to get worked up about. But mosquito control isn’t exactly low stakes: The insects are considered the deadliest animals on the planet. In the US they are known to carry West Nile virus and, occasionally, other diseases. In tropical regions, they can deliver dengue fever, yellow fever, chikungunya, and malaria—the last of which, in 2022, accounted for 608,000 deaths globally, mostly among small children. As climate change pushes the boundaries of the warm, wet regions where many insect species thrive, mosquito-borne illnesses are expected to spread and even worsen. Even where mosquitoes are a mere nuisance, killing or repelling them is a lucrative business. AC2T, Inc., the company that sells Spartan products and also does business as Spartan Mosquito, sold a reported 4.5 million of its Eradicator boxes by the end of 2019. At one point, the company even sponsored a NASCAR racer. And AC2T is just one of many in a sizeable global market: According to market research, mosquito control products—that is, products that aim to kill the pest—may be worth $1.4 billion worldwide by 2027. The mosquito repellant market, where products are designed to drive the insects away rather than kill them, is already worth billions. In the US, those markets are flooded both with products that are effective, and products that simply are not—many of which, due to their mild ingredients, receive minimal oversight from the Environmental Protection Agency. “The implications for human health are not good,” said Immo Hansen, a biologist and mosquito researcher at New Mexico State University. “People might actually think they are protected when they are not.” (Hansen independently tests mosquito products but has not vetted any of Spartan’s wares.) This environment allows products like the Spartan Mosquito Eradicator to thrive. But AC2T, which is based in Mississippi, may be unique in the lengths it has taken to bring its products to market in the US. According to documents obtained through records requests to the EPA and more than a dozen state agricultural departments—some obtained directly by Undark, and others shared by Purrington—representatives from the company have leaned on their political connections to push past regulatory requirements. In an interview in March 2024, Jeremy Hirsch, 46, a co-founder of AC2T, called some of the steps in those regulatory requirements “bureaucratic BS.” Hirsch, a former sandwich shop worker and Army veteran who, by his account, is a self-taught expert in volatile organic compounds and mosquito ecology and behavior, met his co-founder, Christopher Bonner, when they worked together at Bonner Analytical Testing Company, a family-run chemical analytics company. The Spartan Mosquito Eradicator, originally manufactured in a garage, and the more recent Spartan Mosquito Pro Tech. Hannah Yoon/Undark According to AC2T, its new director as of April is Josey Hood, who described herself as Hirsch’s ex-wife and said that Hirsch no longer speaks for the company. But in interviews with Hirsch predating that transition, he described ambitious plans for the company he co-founded. AC2T sold its first Spartan Mosquito Eradicator in Mississippi in 2017 and, not long after, sought to go global. In 2018, according to correspondence from AC2T, the company planned to expand to 54 countries; in 2020, it announced a pilot project to test its products in West Africa, where malaria is a leading cause of death. “Yes ma’am, there were tons of plans,” Hirsch told Undark. If not for the legal challenges, he said, “I’d be all over the place by now.” Indeed, Purrington’s efforts did not go unnoticed. Months after his initial review went live, AC2T filed a defamation lawsuit against the former professor. “My attorneys were the same ones that sued Rolling Stone and won, so they are pretty good at that,” Hirsch said. “And they said all you need is seven specific things that he said that you can prove he knew otherwise at the time he said it, was blatantly false. And we had 13 things.” The company’s own commissioned research indicated that Purrington was right—that the product did not work as suggested. Nevertheless, they pressed ahead. Throughout the lawsuit, the biologist continued his very public—and, to some observers, quixotic—quest to expose what he saw as the company’s misdeeds. He authored more than a dozen blog posts, created an expansive timeline on AC2T’s history, made countless posts on social media, and sent a deluge of emails to the EPA, the Federal Trade Commission, state health departments, Amazon.com, and pesticide managers in the agricultural departments of all 50 states. Soon after the defamation case began, lawyers filed a class action lawsuit against AC2T, which represented plaintiffs who said they had bought a product that did not work; that case reached a preliminary settlement in 2023 for a maximum of $3.6 million and, pending the court’s final decision, may eventually take some of the company’s products off the market. “If you interviewed anyone who followed me on Twitter, they’d roll their eyes and say Purrington, yeah, he just can’t stop posting about these companies,” he said. But he was upset that Spartan had been eyeing the West African market. “No one was going to stop them from getting a foothold in malarial regions,” he said. “And they were going to make a killing.” Humans have cooked up all sorts of ways to battle mosquitos: We spray them with pesticides and larvicides, drain the stagnant water in which they need to breed, zap them, kill them with fish, and even deploy genetically altered mosquitoes to help bring down populations. Some state and national governments, especially in tropical areas, maintain entire divisions devoted to waging systematic campaigns against the insects. At the individual level, health officials urge people to use proven, EPA-registered repellents, to wear long sleeves and pants, and to avoid going outdoors when mosquitoes are most active. Some of these approaches are easy for anyone to do without much or any government oversight. Others are regulated, including the production of pesticides, which are mainly the responsibility of the EPA under the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA. “I think there are some companies that do take advantage of not having to do EPA registrations.” But within the world of pesticides, there is a murky category: Those that are exempt from EPA registration because their ingredients are considered generally safe to use. These “minimum risk” ingredients, as they are called, include essential oils, putrid eggs, certain salts, and more. “EPA has kind of washed their hands” of such products, said Daniel Markowski, the technical adviser for the American Mosquito Control Association. Some exempt products can in fact kill insects, said Jerome Goddard, a medical entomologist at Mississippi State University. But the products only work if “they get on the bug. They kill on contact,” he said. The problem, Goddard said, is that the active ingredients in these unregulated products often don’t stick around in the environment long enough to be effective. Another issue: “Some of these manufacturers make exorbitant claims that just aren’t true.” (Goddard declined to speak on the record about AC2T or its products.) Companies that want to sell EPA-exempt repellents or pesticides still need to register with individual states—though in some, the oversight is fairly cursory: Regulators simply make sure that the ingredients on a product’s label are indeed on the minimum risk list, that it follows the basic rules outlined by the law, and that it doesn’t include any outrageous claims about how well it works, including big claims related to human health. Others require data proving that the products work, including Mississippi, AC2T’s home state. The exempt products—often called 25(b)s, for the section of FIFRA under which they fall—are notoriously difficult for state regulators to evaluate. In emails obtained by Undark, Denise Clanton, a former branch director at the Mississippi Department of Agriculture and Commerce, Bureau of Plant Industry, complained to colleagues in other states about the difficulty of enforcing those laws. “We have such a difficult job with these 25b products when it comes to questionable claims because we have such small amounts of guidance in certain areas,” she wrote. Spartan Mosquito even sponsored a NASCAR racer. Chris Graythen/Getty Images Many experts, including representatives from the American Mosquito Control Association, the Association of American Pesticide Control Officials, and individual state officials, say that this system is broken—creating a glut of exempt products with wildly varying effectiveness and inconsistent oversight. “The 25(b) regulation is tricky for states,” said Sarah Caffery, the pesticide product registration manager for the Office of Indiana State Chemist. “It creates a lot more resource needs from states to ensure they are reviewed at the highest level needed.” “I think there are some companies that do take advantage of not having to do EPA registrations,” she added. Regulators have cracked down on some of these products. For instance, in 2015, the Federal Trade Commission charged a company with making false claims about a wristband that contained mint oil, which supposedly warded off mosquitoes; the company settled with the agency the next year for $300,000. In 2018, the FTC settled with a New Jersey business for claiming that its perfumes and candles could repel Zika-carrying mosquitoes. And while the American Mosquito Control Association doesn’t take a stance on specific products, it generally advises the public to stick with those that are EPA-approved. (Hirsch described the American Mosquito Control Association as a “neurotoxin lobby group.”) In 2021, the EPA announced that it was considering a change to 25(b) products, perhaps by streamlining the registration process or amending current exemptions, prompting dozens of public responses. To date, the agency has not publicly disclosed how or whether the regulations will change, and there is no official deadline as to when its review will be complete. It is against this backdrop that the Spartan Mosquito Eradicator landed. In 2016, Jeremy Hirsch was working at a sandwich shop called Which Wich Superior in Hattiesburg, Mississippi. Around that time, as he recalled in an interview with Undark, he got the idea to make a product to control mosquitoes when he saw his then-pregnant wife readying to spray down one of their children with insect repellent and thought to himself: “There has got to be an easier way.” “I started reading a lot online, just everything I could about mosquitoes in general,” said Hirsch. “How long they live, you know. What they’re attracted to. How their important systems work, like muscular and neuro systems, et cetera.” First, he made a spray to put on, say, the yard to keep mosquitoes at bay. The spray contained boric acid—a pesticide widely used to kill ants, roaches, and other pests. “Turns out it kills everything, kind of indiscriminately,” he said. Then he tried stuffing boric acid and other ingredients into black socks and black painted water bottles, the color of which may attract the insects. These too, he said, killed any insect that came into contact with them. After some more experimentation—and some consultations with Chris Bonner, who had previously worked with Hirsch during the latter’s stint at his family’s chemical company—Hirsch came up with the black and orange tubes for the Spartan Mosquito Eradicator. Later in 2016, the two men formed AC2T, named, Hirsch said, for the first initials of their respective children, and started manufacturing the product in a garage. Purrington pours the powder from a Spartan Mosquito Pro Tech tube, which contains sugar, yeast, and boric acid. Experts have raised concerns that the combination of yeast and sugar, used to lure the mosquitos, may not work as intended. Hannah Yoon/Undark Purrington hangs a Spartan tube in his backyard. He is the only scientist not affiliated with AC2T that Undark was able to find who has tested the Spartan Pro Tech in the wild. His conclusion is that it does not work. Hannah Yoon/Undark At the time, the Spartan Mosquito Eradicator contained sugar, yeast, and boric acid. Users could add warm water to the product’s tube, prompting the yeast to activate and chomp some of the sugar to emit carbon dioxide (mosquitoes are attracted to the CO2 in a person’s breath). The mosquitoes would then enter the tube through one of several tiny holes to feed on the remaining sweet liquid inside—females eat blood when they need protein to lay their eggs, but both females and males also regularly eat sugary nectar—while also ingesting the boric acid. The product, the company claimed, would kill mosquitoes at a rate of 95 percent. AC2T was soon peddling its product to local officials. In late September 2016, for instance, Joseph “Jody” Waits, a Lamar county administrator and family friend of Bonner’s, invited AC2T to hang the Spartan Mosquito Eradicator in a Mississippi neighborhood that had a case of Zika. The county’s mosquito control unit had “fogged the area” for four days, according to internal documents—including, according to an interview with Waits, the area in which AC2T hung its products. The number of mosquitoes subsequently dropped. AC2T later called the occurrence a “case study,” claiming it was the Spartan Mosquito Eradicator that had succeeded in wiping out the local mosquitoes. The company also suggested in advertising materials that their work was endorsed by the state’s health department, which the latter denied. The advertisement drew a warning from the Mississippi Attorney General. (Lamar County eventually purchased 500 Spartan Mosquito Eradicators.) By 2017, AC2T was selling its boric-acid-based product locally. And in early April 2017, Hirsch promoted the Spartan Mosquito Eradicator to the Hattiesburg City Council, for possible use in the city. “The poison levels in there—it’s a poison called boron, or borax,” he told the officials. “We’re to the point now, and we should be able to finalize this in the coming weeks, where there is zero poison in it whatsoever.” (Both boric acid and the household cleaner borax are compounds that contain boron, but they’re not interchangeable.) Hirsch had been looking to drop boric acid from the product because the pesticide falls under EPA regulation—and AC2T had not gone through the required registration. Hirsch argues to this day that his original product had less boric acid than lipstick, silly putty, and other common products. “It seemed innocuous to us,” he told Undark. He also insists that, at the time, AC2T had repeatedly asked the agency for guidance on whether boric acid required registration, without response. An email dated April 10, 2017, from the EPA’s Region 4, which oversees Mississippi, however, clarifies to Hirsch: “Regarding your product, based on what you’ve described, it would be considered a ‘pesticide’ according to the Federal Insecticide, Rodenticide and Fungicide Act (FIFRA).” Without federal approval for its boric acid product, the company swapped the ingredient for table salt, maintained its claim that the new product would kill 95 percent of mosquitoes, and applied for a 25(b) registration in Mississippi and a handful of other states. As proof that the product worked, the company sent Mississippi regulators a 15-page paper with Hirsch as the sole author, sponsor, study director, and test subject. Clanton, the state employee responsible for approving pesticides for sale, granted the registration, although, in a later email to a fellow pesticide regulator in Maine, she said she had not wanted to do so but that “the call was out of my hands.” (When reached by phone, Clanton said: “I do not want to talk about that product” and hung up.) In this 2019 video, Jeremy Hirsch, co-founder of Spartan Mosquito, describes one of his products for a local news station. Scientific evidence puts AC2T’s claims about its salt-based formulation into question—including research by independent scientists that the company hired to investigate whether its tubes actually worked. One of those scientists is Donald Yee, a mosquito ecologist at the University of Southern Mississippi. Yee would not speak directly about AC2T or its employees. “As you may know they are very litigious, and have been ‘hostile’ to me in the past,” he wrote in an email to Undark. But in legal filings related to the class action suit against AC2T, Yee has recounted some of his experiences working with the company: After he disclosed his research findings, which showed that the Spartan Mosquito Eradicator did not work, Hirsch engaged in what Yee’s attorneys described in a legal brief as “bullying tactics.” “I stormed out last time and said fine, Mississippi will look like the dummies who allow the product to be sold and manufactured here.” Yee did speak to Undark in generalities about the ingredients within such a device. In a phone interview, he noted that the combination was unlikely to kill mosquitoes for several reasons: The amount of CO2 produced by a small bit of yeast isn’t enough to draw swarms of mosquitoes; the sugar water wouldn’t be more attractive than the numerous nearby blooms from gardens and wild plants; the salt, which is a major component of human blood, wasn’t lethal. Some scientists, including Purrington, also say that mosquitoes cannot fit through the holes in AC2T’s products, a claim that the company has disputed. Another scientist who tested the product, Rui-De Xue, the director of the Anastasia Mosquito Control District in Florida, declined an interview request. “Sorry I cannot discuss with you about this product,” he wrote to Undark by email, noting that he was “tired of the lawsuit and cost.” Both Yee and Xue have, however, published relevant peer-reviewed research. In a study published in 2020, Yee teamed up with scientists across five separate labs to determine whether or not table salt could kill mosquitoes; it did not, and the findings were consistent across nine mosquito species that bite humans, including several that spread disease. And in early 2021, Xue, along with several colleagues, published the results of tests of AC2T’s salt-based product on one mosquito species. “Both laboratory and field components of our study show that the Spartan Mosquito Eradicator is not effective in reducing abundance,” the researchers concluded. Unpublished research performed upon AC2T’s request also suggested that the product would not work. An October 2019 report from Hirsch’s former employer, Bonner Analytical—completed about two months before AC2T sued Purrington for defamation—examined the CO2 that the yeast in the Eradicator emitted. The company concluded: “Based on all of our available research our product never produces enough CO2 to meet the burden of proof for mosquito attraction.” In a March 2024 phone call with Undark, which lasted more than an hour, Hirsch defended the company’s products. “No one in their right mind would say, well, mosquitoes aren’t attracted to stagnant water,” he said, responding to claims that the product’s yeasty liquid does not attract mosquitos. And in a two-hour follow-up interview in early June, Hirsch stressed that any test on just one element of the product—including the Bonner CO2 findings—isn’t enough to prove that the product doesn’t work: “Things don’t happen in a vacuum. You’re addressing one out of the 10 things that attract mosquitoes to that device, ok?” In regards to whether any test could ever definitely prove the efficacy of any mosquito product—including his—he said in an earlier interview: “If they go away, does that mean that it works? I don’t know.” By the end of 2018, Spartan was available for sale in at least 47 states, and the company was growing so quickly that it moved to a 63,000-square-foot production facility in Laurel, Mississippi. But emails suggest that the company had already begun encountering headwinds, as state officials grew wary of the Eradicator—often following email alerts from Purrington—as well as a new product from AC2T called Sock-It-Skeeter, which contained the same salt-based ingredients. (Hood, the company’s current director, told Undark that the Sock-It-Skeeter never made it to market.) Regulators began pulling back on registrations, some citing the lack of efficacy data, and others citing inconsistencies and false health-related claims on the respective 25(b) labels. At the same time, state records and interviews indicate, AC2T representatives were appealing to elected officials for help. In at least three states, lawmakers stepped in to defend the company, urging regulatory agencies to give AC2T special consideration or questioning their decisions. In 2018 in Maine, for instance, when the state pesticide registrar at the time, Mary Tomlinson, was facing a months-long backlog of 25(b) products needing review, a sales manager at AC2T “contacted a legislator here to get it pushed up to the front, who then contacted our commissioner,” she wrote in an email to Clanton, the Mississippi official. (Tomlinson declined an interview request.) The pressure campaign echoed what Clanton seems to have experienced in Mississippi. “I was told from above to approve,” she said in another email from 2018. In a June 2019 email, she told colleagues in other states that she had been told to “expedite a review” for Sock-It-Skeeter. “I am having to prove myself over and over due to the political push from these people,” she wrote. And in a message from November 2019, Clanton vented to Caffery in Indiana about the Spartan Mosquito Eradicator and the Sock-It-Skeeter. “Every time I mention issues with those two products, I get ‘that look’ like drop it. So, I give up,” she wrote. “I stormed out last time and said fine, Mississippi will look like the dummies who allow the product to be sold and manufactured here. More importantly, I look like the dummy bc I’m the registration person which makes me even more angry.” (Although Undark interviewed Caffery, she declined to speak about her experiences with AC2T on the record.) A written statement from Robert Graves, the Mississippi Special Assistant Attorney General, said in part that the states agricultural department “has complied with all the requirements” for registering the Spartan Mosquito products. The agency did not respond to specific questions from Undark regarding pressure from ACT2T, stating: “we are simply unable to continue to devote our limited resources to your investigation.” Even as the company faced pushback, it prepared to launch a new product—again seeking help from elected officials. In 2018, documents suggest that the company was readying a product that would use boric acid instead of salt. According to documents obtained through a records request, a letter from Christopher Spence, then the chief financial officer at Spartan Mosquito, to Scott Pruitt, then head of the EPA, asked for a waiver to get the product fast-tracked for federal approval. Spence wrote a similar letter to Mississippi Senator Cindy Hyde-Smith, who had previously served as the state’s Commissioner of Agriculture and Commerce. “I took all the technology and everything we learned…I handed it to the president of Togo and said: Do with it what you will.” Should the company be able to legally add boric acid to their product, the letters claimed, they would be able to kill every single species of mosquito on the planet, including those that spread disease. The letter also noted that it had escalated its concerns with pesticide registration all the way up to the White House, referring to an attached letter from Trump in support of the company. (The Trump letter itself has not been released. Hirsch declined to share the letter, but told Undark that it said, in reference to regulators: “Good luck with everything, and just keep talking to them.”) Around this time, the company began considering overseas markets, too. In the letters to Pruitt and Hyde-Smith, AC2T noted plans to enter 54 countries. In 2019, Hirsch was attending social events with then-Mississippi Gov. Phil Bryant and the American Chamber of Commerce-Ghana; in 2020, Hirsch was working with officials in Togo, in West Africa, where malaria is the leading cause of death, to test AC2T’s product. “We are so pleased to partner with Spartan Mosquito to promote effective new mosquito-control solutions in Togo,” the Minister of Health and Public Hygiene Professor Moustafa Mijiyawa said in a press release. (Mijiyawa did not respond to a request for an interview, nor did Tinah Atcha-Oubou, the coordinator for Togo’s National Malaria Control Program.) According to Hirsch, in Togo, he was initially giving his products and other expertise away for free: “I took all the technology and everything we learned, I put it in a book, and I handed it to the president of Togo and said: Do with it what you will.” Whether a boric acid-based product like the Spartan Pro Tech would work any better than salt-based ones is unclear. On one hand, boric acid is a known pesticide and, if ingested, it will kill a mosquito. Xue and many other experts have published research on toxic baits that contain both sugar and boric acid, and found that, at least in highly controlled laboratory settings, the combination is lethal to at least some species. Field studies on mosquito baits that are laced with boric acid have had mixed results. But the concerns that experts have raised over the yeast and sugar combination, which are used in the Pro Tech to lure and feed the mosquitoes, respectively, remain relevant. While experts do use CO2 as a mosquito lure, it typically requires pounds of dry ice, which dissipates entirely overnight, several experts told Undark. By comparison, the Spartan products contain about a teaspoon of yeast, and the company claims that the product will last for 90 days. The company’s own report from Bonner Analytical noted that the previous product, the Spartan Mosquito Eradicator, did not contain enough yeast for a lure; the amount of yeast in both products appear to be roughly the same, according to reports submitted to the EPA. The EPA approved registration of the Spartan Mosquito Pro Tech in March 2020. In an email message to Purrington later that year, Erik Kraft, an EPA scientist who, at the time, was in charge of boric acid products, wrote: “In the case of Spartan Mosquito Pro Tech, EPA reviewed studies on the product’s acute toxicity, product chemistry and efficacy and found these data to be acceptable and therefore registered the product.” A review of the scientific data submitted in support of the Spartan Pro Tech shows that an independent research company performed lab tests which, in line with the broader scientific literature, confirm that when mosquitoes eat boric acid, they die. Field tests were performed by Bonner Analytical Testing Company, the chemical analysis company where Chris Bonner, the co-founder of AC2T is employed, and the analysis report was co-authored by Chris; his father Michael Bonner; and Hirsch. “I spent four years in the Pennsylvania courts” and was “tired of paying fucking lawyers.” The report only briefly describes several field tests and has scant methodological information or analysis. In response to queries about Spartan Pro Tech efficacy data, Jeffrey Landis, an EPA spokesperson, wrote via email: “A comprehensive review was completed on the study reports submitted in support of the Spartan Pro Tech application. The review team determined that the conditions under which those studies were conducted were adequate to assure the quality, validity, and integrity of the data.”    The EPA did not review any documents related to the CO2 produced by the Spartan Pro Tech. “Attractancy claims, which would have been supported in part by acceptable CO2 data, are not included on the EPA-approved label; therefore, no data were required for those specific claims,” Landis wrote via email. Undark was unable to find any scientist who isn’t affiliated with AC2T who has tested the Spartan Pro Tech in the wild—aside from Purrington. On Purrington’s website, his withering review provides his own answer as to whether it works: “No.” Pending the outcome of the class action settlement agreement, the company may have to halt sales of both products, at least in the United States. According to the proposed settlement agreement, which reads, in part, that it is “the product of extensive, arms-length, and vigorously contested settlement discussions,” AC2T will be prohibited from selling the salt-based Spartan Mosquito Eradicator. To sell the boric-acid-based Spartan Mosquito Pro Tech, meanwhile, the company would have 18 months to conduct additional research proving that it works. Speaking prior to Hood’s takeover as the new director of the company, Hirsch suggested that wouldn’t be a problem: “We run hundreds of tests a year. We aren’t going to stop doing what we’re doing.” In a subsequent email, Hood noted that AC2T runs product tests several times a year, not hundreds. The company did not respond to multiple requests to share data from of any of those tests with Undark. Due at least in part to AC2T’s legal woes, which Hirsch said cost him $7 million and pushed him out of his job, the company is not making any moves into the international market. Any mention of AC2T’s expansion into West Africa—or elsewhere outside of the US—has quietly disappeared from the company’s website and literature, and a separate website for a related nonprofit, the Innovative Mosquito Control Incorporated, is also gone. For his part, Hirsch insists that the many actions against AC2T are part of a wider effort by the mosquito control industry to push a small competitor out of the market. As for the company’s own hopes for the future, Hood stressed to Undark: “We plan to continue to manufacture and sell to our customers. We believe in our product. We’ve hit some stumbles just as any young companies do, but we are optimistic for the future.” Indeed, the future of AC2T in the US is far from clear. Emails among state and federal employees, as well as other documents, suggest that the EPA could be investigating the company. (Both the EPA and the Federal Trade Commission declined to respond to questions about any potential investigations.) Earlier this year, attorneys representing AC2T in the class action suit dropped the company as a client, citing a failure to pay their legal bills. The legal team representing AC2T in its defamation suit against Purrington had done the same. (Hirsch told Undark: “I spent four years in the Pennsylvania courts” and was “tired of paying fucking lawyers.” Hood told Undark that she thought the lawsuit was without merit, and that as the new director of the company, she decided “not to pursue the case.”) In mid-March, the judge dismissed the defamation case against Purrington with prejudice. Purrington says he spent more than $90,000 preparing for trial—money he’s trying to recoup, at least in part, in a lawsuit against AC2T, which he filed on May 14, 2024. But when he reflects more broadly on his ordeal, the scientist’s irritations reach well beyond the company. “I’m mad that they sued me,” Purrington said. “But I’m just kind of disappointed at the rest of the world for not caring as much as I do.”

In 2019, Colin Purrington, an evolutionary biologist, was scrolling through the internet when he came across something that would change his life. Purrington, 57, who left a professor position at Swarthmore College in 2011 to spend more time with his family, dabbles these days: He snaps nature photography, gives presentations at the local farmer’s market, […]

In 2019, Colin Purrington, an evolutionary biologist, was scrolling through the internet when he came across something that would change his life.

Purrington, 57, who left a professor position at Swarthmore College in 2011 to spend more time with his family, dabbles these days: He snaps nature photography, gives presentations at the local farmer’s market, and occasionally reviews products for his personal blog. On that fateful day in 2019, a new product had caught his eye: The Spartan Mosquito Eradicator, a roughly foot-long black and orange tube with a Corinthian helmet emblazoned on the side, its plumes replaced by mosquito wings. Inside was a mixture of sugar, yeast, and salt.

“I was intrigued, given that it said that it could kill 95 percent of mosquitoes,” Purrington recalled in an interview with Undark. The claims seemed too good to be true, he thought, so he decided to try it out.

After purchasing two tubes for about $25, Purrington hung them in his yard in Pennsylvania and checked them, he says, more than a 100 times over the summer. But he didn’t see much happen, a fact that compelled him to write a nearly 4,000-word review on his personal website.

To say it was a pan is an understatement. “The Spartan Mosquito Eradicator is unlikely to kill a single mosquito unless it falls from the tree and lands on one,” Purrington wrote. He called some of the company’s claims “idiotic.” He also laid out a lengthy case that the company had misled regulators about the efficacy of its product, lied to customers, and broken some laws—and encouraged readers to contact regulators and file complaints.

“My attorneys were the same ones that sued Rolling Stone and won, so they are pretty good at that.”

A tube of baking ingredients might not seem like much to get worked up about. But mosquito control isn’t exactly low stakes: The insects are considered the deadliest animals on the planet. In the US they are known to carry West Nile virus and, occasionally, other diseases. In tropical regions, they can deliver dengue fever, yellow fever, chikungunya, and malaria—the last of which, in 2022, accounted for 608,000 deaths globally, mostly among small children. As climate change pushes the boundaries of the warm, wet regions where many insect species thrive, mosquito-borne illnesses are expected to spread and even worsen.

Even where mosquitoes are a mere nuisance, killing or repelling them is a lucrative business. AC2T, Inc., the company that sells Spartan products and also does business as Spartan Mosquito, sold a reported 4.5 million of its Eradicator boxes by the end of 2019. At one point, the company even sponsored a NASCAR racer. And AC2T is just one of many in a sizeable global market: According to market research, mosquito control products—that is, products that aim to kill the pest—may be worth $1.4 billion worldwide by 2027. The mosquito repellant market, where products are designed to drive the insects away rather than kill them, is already worth billions.

In the US, those markets are flooded both with products that are effective, and products that simply are not—many of which, due to their mild ingredients, receive minimal oversight from the Environmental Protection Agency. “The implications for human health are not good,” said Immo Hansen, a biologist and mosquito researcher at New Mexico State University. “People might actually think they are protected when they are not.” (Hansen independently tests mosquito products but has not vetted any of Spartan’s wares.)

This environment allows products like the Spartan Mosquito Eradicator to thrive. But AC2T, which is based in Mississippi, may be unique in the lengths it has taken to bring its products to market in the US.

According to documents obtained through records requests to the EPA and more than a dozen state agricultural departments—some obtained directly by Undark, and others shared by Purrington—representatives from the company have leaned on their political connections to push past regulatory requirements. In an interview in March 2024, Jeremy Hirsch, 46, a co-founder of AC2T, called some of the steps in those regulatory requirements “bureaucratic BS.” Hirsch, a former sandwich shop worker and Army veteran who, by his account, is a self-taught expert in volatile organic compounds and mosquito ecology and behavior, met his co-founder, Christopher Bonner, when they worked together at Bonner Analytical Testing Company, a family-run chemical analytics company.

The Spartan Mosquito Eradicator, originally manufactured in a garage, and the more recent Spartan Mosquito Pro Tech. Hannah Yoon/Undark

According to AC2T, its new director as of April is Josey Hood, who described herself as Hirsch’s ex-wife and said that Hirsch no longer speaks for the company. But in interviews with Hirsch predating that transition, he described ambitious plans for the company he co-founded. AC2T sold its first Spartan Mosquito Eradicator in Mississippi in 2017 and, not long after, sought to go global. In 2018, according to correspondence from AC2T, the company planned to expand to 54 countries; in 2020, it announced a pilot project to test its products in West Africa, where malaria is a leading cause of death. “Yes ma’am, there were tons of plans,” Hirsch told Undark. If not for the legal challenges, he said, “I’d be all over the place by now.”

Indeed, Purrington’s efforts did not go unnoticed. Months after his initial review went live, AC2T filed a defamation lawsuit against the former professor. “My attorneys were the same ones that sued Rolling Stone and won, so they are pretty good at that,” Hirsch said. “And they said all you need is seven specific things that he said that you can prove he knew otherwise at the time he said it, was blatantly false. And we had 13 things.”

The company’s own commissioned research indicated that Purrington was right—that the product did not work as suggested. Nevertheless, they pressed ahead.

Throughout the lawsuit, the biologist continued his very public—and, to some observers, quixotic—quest to expose what he saw as the company’s misdeeds. He authored more than a dozen blog posts, created an expansive timeline on AC2T’s history, made countless posts on social media, and sent a deluge of emails to the EPA, the Federal Trade Commission, state health departments, Amazon.com, and pesticide managers in the agricultural departments of all 50 states. Soon after the defamation case began, lawyers filed a class action lawsuit against AC2T, which represented plaintiffs who said they had bought a product that did not work; that case reached a preliminary settlement in 2023 for a maximum of $3.6 million and, pending the court’s final decision, may eventually take some of the company’s products off the market.

“If you interviewed anyone who followed me on Twitter, they’d roll their eyes and say Purrington, yeah, he just can’t stop posting about these companies,” he said. But he was upset that Spartan had been eyeing the West African market. “No one was going to stop them from getting a foothold in malarial regions,” he said. “And they were going to make a killing.”

Humans have cooked up all sorts of ways to battle mosquitos: We spray them with pesticides and larvicides, drain the stagnant water in which they need to breed, zap them, kill them with fish, and even deploy genetically altered mosquitoes to help bring down populations. Some state and national governments, especially in tropical areas, maintain entire divisions devoted to waging systematic campaigns against the insects. At the individual level, health officials urge people to use proven, EPA-registered repellents, to wear long sleeves and pants, and to avoid going outdoors when mosquitoes are most active.

Some of these approaches are easy for anyone to do without much or any government oversight. Others are regulated, including the production of pesticides, which are mainly the responsibility of the EPA under the Federal Insecticide, Fungicide, and Rodenticide Act, or FIFRA.

“I think there are some companies that do take advantage of not having to do EPA registrations.”

But within the world of pesticides, there is a murky category: Those that are exempt from EPA registration because their ingredients are considered generally safe to use. These “minimum risk” ingredients, as they are called, include essential oils, putrid eggs, certain salts, and more. “EPA has kind of washed their hands” of such products, said Daniel Markowski, the technical adviser for the American Mosquito Control Association.

Some exempt products can in fact kill insects, said Jerome Goddard, a medical entomologist at Mississippi State University. But the products only work if “they get on the bug. They kill on contact,” he said. The problem, Goddard said, is that the active ingredients in these unregulated products often don’t stick around in the environment long enough to be effective. Another issue: “Some of these manufacturers make exorbitant claims that just aren’t true.” (Goddard declined to speak on the record about AC2T or its products.)

Companies that want to sell EPA-exempt repellents or pesticides still need to register with individual states—though in some, the oversight is fairly cursory: Regulators simply make sure that the ingredients on a product’s label are indeed on the minimum risk list, that it follows the basic rules outlined by the law, and that it doesn’t include any outrageous claims about how well it works, including big claims related to human health. Others require data proving that the products work, including Mississippi, AC2T’s home state.

The exempt products—often called 25(b)s, for the section of FIFRA under which they fall—are notoriously difficult for state regulators to evaluate. In emails obtained by Undark, Denise Clanton, a former branch director at the Mississippi Department of Agriculture and Commerce, Bureau of Plant Industry, complained to colleagues in other states about the difficulty of enforcing those laws. “We have such a difficult job with these 25b products when it comes to questionable claims because we have such small amounts of guidance in certain areas,” she wrote.

Spartan Mosquito even sponsored a NASCAR racer. Chris Graythen/Getty Images

Many experts, including representatives from the American Mosquito Control Association, the Association of American Pesticide Control Officials, and individual state officials, say that this system is broken—creating a glut of exempt products with wildly varying effectiveness and inconsistent oversight. “The 25(b) regulation is tricky for states,” said Sarah Caffery, the pesticide product registration manager for the Office of Indiana State Chemist. “It creates a lot more resource needs from states to ensure they are reviewed at the highest level needed.”

“I think there are some companies that do take advantage of not having to do EPA registrations,” she added.

Regulators have cracked down on some of these products. For instance, in 2015, the Federal Trade Commission charged a company with making false claims about a wristband that contained mint oil, which supposedly warded off mosquitoes; the company settled with the agency the next year for $300,000. In 2018, the FTC settled with a New Jersey business for claiming that its perfumes and candles could repel Zika-carrying mosquitoes. And while the American Mosquito Control Association doesn’t take a stance on specific products, it generally advises the public to stick with those that are EPA-approved. (Hirsch described the American Mosquito Control Association as a “neurotoxin lobby group.”)

In 2021, the EPA announced that it was considering a change to 25(b) products, perhaps by streamlining the registration process or amending current exemptions, prompting dozens of public responses. To date, the agency has not publicly disclosed how or whether the regulations will change, and there is no official deadline as to when its review will be complete.

It is against this backdrop that the Spartan Mosquito Eradicator landed.

In 2016, Jeremy Hirsch was working at a sandwich shop called Which Wich Superior in Hattiesburg, Mississippi. Around that time, as he recalled in an interview with Undark, he got the idea to make a product to control mosquitoes when he saw his then-pregnant wife readying to spray down one of their children with insect repellent and thought to himself: “There has got to be an easier way.”

“I started reading a lot online, just everything I could about mosquitoes in general,” said Hirsch. “How long they live, you know. What they’re attracted to. How their important systems work, like muscular and neuro systems, et cetera.”

First, he made a spray to put on, say, the yard to keep mosquitoes at bay. The spray contained boric acid—a pesticide widely used to kill ants, roaches, and other pests. “Turns out it kills everything, kind of indiscriminately,” he said. Then he tried stuffing boric acid and other ingredients into black socks and black painted water bottles, the color of which may attract the insects. These too, he said, killed any insect that came into contact with them.

After some more experimentation—and some consultations with Chris Bonner, who had previously worked with Hirsch during the latter’s stint at his family’s chemical company—Hirsch came up with the black and orange tubes for the Spartan Mosquito Eradicator. Later in 2016, the two men formed AC2T, named, Hirsch said, for the first initials of their respective children, and started manufacturing the product in a garage.

Purrington pours the powder from a Spartan Mosquito Pro Tech tube, which contains sugar, yeast, and boric acid. Experts have raised concerns that the combination of yeast and sugar, used to lure the mosquitos, may not work as intended. Hannah Yoon/Undark
Purrington hangs a Spartan tube in his backyard. He is the only scientist not affiliated with AC2T that Undark was able to find who has tested the Spartan Pro Tech in the wild. His conclusion is that it does not work. Hannah Yoon/Undark

At the time, the Spartan Mosquito Eradicator contained sugar, yeast, and boric acid. Users could add warm water to the product’s tube, prompting the yeast to activate and chomp some of the sugar to emit carbon dioxide (mosquitoes are attracted to the CO2 in a person’s breath). The mosquitoes would then enter the tube through one of several tiny holes to feed on the remaining sweet liquid inside—females eat blood when they need protein to lay their eggs, but both females and males also regularly eat sugary nectar—while also ingesting the boric acid. The product, the company claimed, would kill mosquitoes at a rate of 95 percent.

AC2T was soon peddling its product to local officials. In late September 2016, for instance, Joseph “Jody” Waits, a Lamar county administrator and family friend of Bonner’s, invited AC2T to hang the Spartan Mosquito Eradicator in a Mississippi neighborhood that had a case of Zika. The county’s mosquito control unit had “fogged the area” for four days, according to internal documents—including, according to an interview with Waits, the area in which AC2T hung its products. The number of mosquitoes subsequently dropped.

AC2T later called the occurrence a “case study,” claiming it was the Spartan Mosquito Eradicator that had succeeded in wiping out the local mosquitoes. The company also suggested in advertising materials that their work was endorsed by the state’s health department, which the latter denied. The advertisement drew a warning from the Mississippi Attorney General. (Lamar County eventually purchased 500 Spartan Mosquito Eradicators.)

By 2017, AC2T was selling its boric-acid-based product locally. And in early April 2017, Hirsch promoted the Spartan Mosquito Eradicator to the Hattiesburg City Council, for possible use in the city. “The poison levels in there—it’s a poison called boron, or borax,” he told the officials. “We’re to the point now, and we should be able to finalize this in the coming weeks, where there is zero poison in it whatsoever.” (Both boric acid and the household cleaner borax are compounds that contain boron, but they’re not interchangeable.)

Hirsch had been looking to drop boric acid from the product because the pesticide falls under EPA regulation—and AC2T had not gone through the required registration. Hirsch argues to this day that his original product had less boric acid than lipstick, silly putty, and other common products. “It seemed innocuous to us,” he told Undark. He also insists that, at the time, AC2T had repeatedly asked the agency for guidance on whether boric acid required registration, without response. An email dated April 10, 2017, from the EPA’s Region 4, which oversees Mississippi, however, clarifies to Hirsch: “Regarding your product, based on what you’ve described, it would be considered a ‘pesticide’ according to the Federal Insecticide, Rodenticide and Fungicide Act (FIFRA).”

Without federal approval for its boric acid product, the company swapped the ingredient for table salt, maintained its claim that the new product would kill 95 percent of mosquitoes, and applied for a 25(b) registration in Mississippi and a handful of other states. As proof that the product worked, the company sent Mississippi regulators a 15-page paper with Hirsch as the sole author, sponsor, study director, and test subject. Clanton, the state employee responsible for approving pesticides for sale, granted the registration, although, in a later email to a fellow pesticide regulator in Maine, she said she had not wanted to do so but that “the call was out of my hands.” (When reached by phone, Clanton said: “I do not want to talk about that product” and hung up.)

In this 2019 video, Jeremy Hirsch, co-founder of Spartan Mosquito, describes one of his products for a local news station.

Scientific evidence puts AC2T’s claims about its salt-based formulation into question—including research by independent scientists that the company hired to investigate whether its tubes actually worked. One of those scientists is Donald Yee, a mosquito ecologist at the University of Southern Mississippi. Yee would not speak directly about AC2T or its employees.

“As you may know they are very litigious, and have been ‘hostile’ to me in the past,” he wrote in an email to Undark. But in legal filings related to the class action suit against AC2T, Yee has recounted some of his experiences working with the company: After he disclosed his research findings, which showed that the Spartan Mosquito Eradicator did not work, Hirsch engaged in what Yee’s attorneys described in a legal brief as “bullying tactics.”

“I stormed out last time and said fine, Mississippi will look like the dummies who allow the product to be sold and manufactured here.”

Yee did speak to Undark in generalities about the ingredients within such a device. In a phone interview, he noted that the combination was unlikely to kill mosquitoes for several reasons: The amount of CO2 produced by a small bit of yeast isn’t enough to draw swarms of mosquitoes; the sugar water wouldn’t be more attractive than the numerous nearby blooms from gardens and wild plants; the salt, which is a major component of human blood, wasn’t lethal. Some scientists, including Purrington, also say that mosquitoes cannot fit through the holes in AC2T’s products, a claim that the company has disputed.

Another scientist who tested the product, Rui-De Xue, the director of the Anastasia Mosquito Control District in Florida, declined an interview request. “Sorry I cannot discuss with you about this product,” he wrote to Undark by email, noting that he was “tired of the lawsuit and cost.”

Both Yee and Xue have, however, published relevant peer-reviewed research. In a study published in 2020, Yee teamed up with scientists across five separate labs to determine whether or not table salt could kill mosquitoes; it did not, and the findings were consistent across nine mosquito species that bite humans, including several that spread disease. And in early 2021, Xue, along with several colleagues, published the results of tests of AC2T’s salt-based product on one mosquito species. “Both laboratory and field components of our study show that the Spartan Mosquito Eradicator is not effective in reducing abundance,” the researchers concluded.

Unpublished research performed upon AC2T’s request also suggested that the product would not work. An October 2019 report from Hirsch’s former employer, Bonner Analytical—completed about two months before AC2T sued Purrington for defamation—examined the CO2 that the yeast in the Eradicator emitted. The company concluded: “Based on all of our available research our product never produces enough CO2 to meet the burden of proof for mosquito attraction.”

In a March 2024 phone call with Undark, which lasted more than an hour, Hirsch defended the company’s products. “No one in their right mind would say, well, mosquitoes aren’t attracted to stagnant water,” he said, responding to claims that the product’s yeasty liquid does not attract mosquitos. And in a two-hour follow-up interview in early June, Hirsch stressed that any test on just one element of the product—including the Bonner CO2 findings—isn’t enough to prove that the product doesn’t work: “Things don’t happen in a vacuum. You’re addressing one out of the 10 things that attract mosquitoes to that device, ok?”

In regards to whether any test could ever definitely prove the efficacy of any mosquito product—including his—he said in an earlier interview: “If they go away, does that mean that it works? I don’t know.”

By the end of 2018, Spartan was available for sale in at least 47 states, and the company was growing so quickly that it moved to a 63,000-square-foot production facility in Laurel, Mississippi. But emails suggest that the company had already begun encountering headwinds, as state officials grew wary of the Eradicator—often following email alerts from Purrington—as well as a new product from AC2T called Sock-It-Skeeter, which contained the same salt-based ingredients. (Hood, the company’s current director, told Undark that the Sock-It-Skeeter never made it to market.) Regulators began pulling back on registrations, some citing the lack of efficacy data, and others citing inconsistencies and false health-related claims on the respective 25(b) labels.

At the same time, state records and interviews indicate, AC2T representatives were appealing to elected officials for help.

In at least three states, lawmakers stepped in to defend the company, urging regulatory agencies to give AC2T special consideration or questioning their decisions. In 2018 in Maine, for instance, when the state pesticide registrar at the time, Mary Tomlinson, was facing a months-long backlog of 25(b) products needing review, a sales manager at AC2T “contacted a legislator here to get it pushed up to the front, who then contacted our commissioner,” she wrote in an email to Clanton, the Mississippi official. (Tomlinson declined an interview request.)

The pressure campaign echoed what Clanton seems to have experienced in Mississippi. “I was told from above to approve,” she said in another email from 2018. In a June 2019 email, she told colleagues in other states that she had been told to “expedite a review” for Sock-It-Skeeter. “I am having to prove myself over and over due to the political push from these people,” she wrote.

And in a message from November 2019, Clanton vented to Caffery in Indiana about the Spartan Mosquito Eradicator and the Sock-It-Skeeter. “Every time I mention issues with those two products, I get ‘that look’ like drop it. So, I give up,” she wrote. “I stormed out last time and said fine, Mississippi will look like the dummies who allow the product to be sold and manufactured here. More importantly, I look like the dummy bc I’m the registration person which makes me even more angry.”

(Although Undark interviewed Caffery, she declined to speak about her experiences with AC2T on the record.)

A written statement from Robert Graves, the Mississippi Special Assistant Attorney General, said in part that the states agricultural department “has complied with all the requirements” for registering the Spartan Mosquito products. The agency did not respond to specific questions from Undark regarding pressure from ACT2T, stating: “we are simply unable to continue to devote our limited resources to your investigation.”

Even as the company faced pushback, it prepared to launch a new product—again seeking help from elected officials. In 2018, documents suggest that the company was readying a product that would use boric acid instead of salt. According to documents obtained through a records request, a letter from Christopher Spence, then the chief financial officer at Spartan Mosquito, to Scott Pruitt, then head of the EPA, asked for a waiver to get the product fast-tracked for federal approval. Spence wrote a similar letter to Mississippi Senator Cindy Hyde-Smith, who had previously served as the state’s Commissioner of Agriculture and Commerce.

“I took all the technology and everything we learned…I handed it to the president of Togo and said: Do with it what you will.”

Should the company be able to legally add boric acid to their product, the letters claimed, they would be able to kill every single species of mosquito on the planet, including those that spread disease. The letter also noted that it had escalated its concerns with pesticide registration all the way up to the White House, referring to an attached letter from Trump in support of the company. (The Trump letter itself has not been released. Hirsch declined to share the letter, but told Undark that it said, in reference to regulators: “Good luck with everything, and just keep talking to them.”)

Around this time, the company began considering overseas markets, too. In the letters to Pruitt and Hyde-Smith, AC2T noted plans to enter 54 countries. In 2019, Hirsch was attending social events with then-Mississippi Gov. Phil Bryant and the American Chamber of Commerce-Ghana; in 2020, Hirsch was working with officials in Togo, in West Africa, where malaria is the leading cause of death, to test AC2T’s product. “We are so pleased to partner with Spartan Mosquito to promote effective new mosquito-control solutions in Togo,” the Minister of Health and Public Hygiene Professor Moustafa Mijiyawa said in a press release. (Mijiyawa did not respond to a request for an interview, nor did Tinah Atcha-Oubou, the coordinator for Togo’s National Malaria Control Program.)

According to Hirsch, in Togo, he was initially giving his products and other expertise away for free: “I took all the technology and everything we learned, I put it in a book, and I handed it to the president of Togo and said: Do with it what you will.”

Whether a boric acid-based product like the Spartan Pro Tech would work any better than salt-based ones is unclear. On one hand, boric acid is a known pesticide and, if ingested, it will kill a mosquito. Xue and many other experts have published research on toxic baits that contain both sugar and boric acid, and found that, at least in highly controlled laboratory settings, the combination is lethal to at least some species. Field studies on mosquito baits that are laced with boric acid have had mixed results.

But the concerns that experts have raised over the yeast and sugar combination, which are used in the Pro Tech to lure and feed the mosquitoes, respectively, remain relevant. While experts do use CO2 as a mosquito lure, it typically requires pounds of dry ice, which dissipates entirely overnight, several experts told Undark. By comparison, the Spartan products contain about a teaspoon of yeast, and the company claims that the product will last for 90 days. The company’s own report from Bonner Analytical noted that the previous product, the Spartan Mosquito Eradicator, did not contain enough yeast for a lure; the amount of yeast in both products appear to be roughly the same, according to reports submitted to the EPA.

The EPA approved registration of the Spartan Mosquito Pro Tech in March 2020. In an email message to Purrington later that year, Erik Kraft, an EPA scientist who, at the time, was in charge of boric acid products, wrote: “In the case of Spartan Mosquito Pro Tech, EPA reviewed studies on the product’s acute toxicity, product chemistry and efficacy and found these data to be acceptable and therefore registered the product.”

A review of the scientific data submitted in support of the Spartan Pro Tech shows that an independent research company performed lab tests which, in line with the broader scientific literature, confirm that when mosquitoes eat boric acid, they die. Field tests were performed by Bonner Analytical Testing Company, the chemical analysis company where Chris Bonner, the co-founder of AC2T is employed, and the analysis report was co-authored by Chris; his father Michael Bonner; and Hirsch.

“I spent four years in the Pennsylvania courts” and was “tired of paying fucking lawyers.”

The report only briefly describes several field tests and has scant methodological information or analysis. In response to queries about Spartan Pro Tech efficacy data, Jeffrey Landis, an EPA spokesperson, wrote via email: “A comprehensive review was completed on the study reports submitted in support of the Spartan Pro Tech application. The review team determined that the conditions under which those studies were conducted were adequate to assure the quality, validity, and integrity of the data.”   

The EPA did not review any documents related to the CO2 produced by the Spartan Pro Tech. “Attractancy claims, which would have been supported in part by acceptable CO2 data, are not included on the EPA-approved label; therefore, no data were required for those specific claims,” Landis wrote via email.

Undark was unable to find any scientist who isn’t affiliated with AC2T who has tested the Spartan Pro Tech in the wild—aside from Purrington. On Purrington’s website, his withering review provides his own answer as to whether it works: “No.”

Pending the outcome of the class action settlement agreement, the company may have to halt sales of both products, at least in the United States. According to the proposed settlement agreement, which reads, in part, that it is “the product of extensive, arms-length, and vigorously contested settlement discussions,” AC2T will be prohibited from selling the salt-based Spartan Mosquito Eradicator. To sell the boric-acid-based Spartan Mosquito Pro Tech, meanwhile, the company would have 18 months to conduct additional research proving that it works.

Speaking prior to Hood’s takeover as the new director of the company, Hirsch suggested that wouldn’t be a problem: “We run hundreds of tests a year. We aren’t going to stop doing what we’re doing.” In a subsequent email, Hood noted that AC2T runs product tests several times a year, not hundreds. The company did not respond to multiple requests to share data from of any of those tests with Undark.

Due at least in part to AC2T’s legal woes, which Hirsch said cost him $7 million and pushed him out of his job, the company is not making any moves into the international market. Any mention of AC2T’s expansion into West Africa—or elsewhere outside of the US—has quietly disappeared from the company’s website and literature, and a separate website for a related nonprofit, the Innovative Mosquito Control Incorporated, is also gone.

For his part, Hirsch insists that the many actions against AC2T are part of a wider effort by the mosquito control industry to push a small competitor out of the market. As for the company’s own hopes for the future, Hood stressed to Undark: “We plan to continue to manufacture and sell to our customers. We believe in our product. We’ve hit some stumbles just as any young companies do, but we are optimistic for the future.”

Indeed, the future of AC2T in the US is far from clear. Emails among state and federal employees, as well as other documents, suggest that the EPA could be investigating the company. (Both the EPA and the Federal Trade Commission declined to respond to questions about any potential investigations.) Earlier this year, attorneys representing AC2T in the class action suit dropped the company as a client, citing a failure to pay their legal bills.

The legal team representing AC2T in its defamation suit against Purrington had done the same. (Hirsch told Undark: “I spent four years in the Pennsylvania courts” and was “tired of paying fucking lawyers.” Hood told Undark that she thought the lawsuit was without merit, and that as the new director of the company, she decided “not to pursue the case.”) In mid-March, the judge dismissed the defamation case against Purrington with prejudice.

Purrington says he spent more than $90,000 preparing for trial—money he’s trying to recoup, at least in part, in a lawsuit against AC2T, which he filed on May 14, 2024.

But when he reflects more broadly on his ordeal, the scientist’s irritations reach well beyond the company. “I’m mad that they sued me,” Purrington said. “But I’m just kind of disappointed at the rest of the world for not caring as much as I do.”

Read the full story here.
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Green leader Adrian Ramsay: Labour’s ‘growth v nature’ framing is an outrage

Co-leader says deprioritisation of net zero is ‘extremely dangerous’ as he rejects ‘nimby-in-chief’ characterisationLabour’s push for economic growth at the expense of climate and nature is “extremely dangerous”, the co-leader of the Green party has said.Adrian Ramsay, the MP for Waveney Valley between Norfolk and Suffolk, was one of the five Green MPs elected to parliament last July in their best ever result. He said and his colleagues knew they would be holding Labour to account, but did not expect to be as disappointed as they have been. Continue reading...

Labour’s push for economic growth at the expense of climate and nature is “extremely dangerous”, the co-leader of the Green party has said.Adrian Ramsay, the MP for Waveney Valley between Norfolk and Suffolk, was one of the five Green MPs elected to parliament last July in their best ever result. He said and his colleagues knew they would be holding Labour to account, but did not expect to be as disappointed as they have been.In recent weeks, Labour has given the green light to airport expansion and vowed to change planning rules to deprioritise nature, while ministers have repeatedly disparaged bats and newts and ridiculed measures to protect fish. The chancellor Rachel Reeves has suggested economic growth trumps the government’s legally binding target of reaching net zero emissions by 2050, and there are suggestions the national wealth fund, meant for green projects, will be coopted for defence.Ramsay said: “This whole depiction the government’s coming up with is completely false and actually extremely dangerous, because green spaces are crucial to people’s wellbeing, crucial to the natural environment, and we can and must do development in a way that not just protects nature … the government is signed up to a requirement to restore 30% of land and sea in the UK for nature by 2030.“And when Labour talks about growth versus nature, it sort of castigates communities who are working to protect their community, protect the environment from being trodden on by a planning system that that should be there to protect them, but the government’s looking at removing those safeguards.”Ramsay also questioned whether Boris Johnson was a greener prime minister than Keir Starmer, saying: “[Johnson] did have some understanding of the need to regenerate the natural world, which Labour are very weak on. While there were early signs of some positive moves on renewable energy targets, that’s now being undermined by climate-wrecking decisions around things like airport expansion.”Ramsay, who is co-leader with fellow MP Carla Denyer, has had a bruising start to his parliamentary career. One of his biggest critics has been Ed Miliband, the energy secretary, who has accused him of being against renewable infrastructure.Miliband’s criticisms of Ramsay have resulted in the Green MP being labelled the “UK’s nimby-in-chief” after he used his first day in parliament to call for a pause on plans for a route of 520 pylons passing through his constituency. Ramsay says he is representing his constituents, who want alternatives to pylons to be discussed before they are built. His critics, including Miliband, say alternatives are too slow and expensive to implement and will impede the government in reaching its target to decarbonise the grid by 2030.Before Ramsay was an MP, he was for many years a Green councillor and worked for renewables campaign groups. Of being referred to as a nimby, he said: “I think that the claims are so absurd that they are laughable. I mean, people have called me Mr Renewables, because my whole career and campaigning background since I was a teenager has been in advancing action on climate and in particular action on renewables. I’m the first to say we’ve got to see more renewables.”MPs for the rightwing Reform party have also opposed pylons as part of their drive to cancel net zero, of which Ramsay said: “Reform have jumped on a bandwagon quite recently. There’s been a cross-party group with the other four parties in East Anglia, working on these issues for some time.” He said the party was “selling people a pup” because “they’re trying to pretend that they’re there to support the ordinary person, but their policies would undermine the NHS, allow the ultra-rich plutocrats from abroad to buy up our democracy, and crucially, would stop the drive for net zero, which will bring down people’s bills and keep people’s homes warm.”There are also rumours that Labour is considering weakening plans aimed at ensuring all new homes are powered by renewables. Government sources say new homes will be “technology agnostic”, allowing housebuilders to meet climate targets how they like, rather than mandating solar panels and heat pumps.skip past newsletter promotionThe planet's most important stories. Get all the week's environment news - the good, the bad and the essentialPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotion“It would be an absolute outrage if the Labour government does not require renewable energy in all new homes,” Ramsay said. “People say to me all the time, why on earth are we seeing new homes being built without solar panels, without renewable heating systems? And the only reason the government wouldn’t do this is if they caved into the developers, because it’s a win-win all the way around.”Ramsay said he would continue to challenge Miliband. “My challenge to Ed Miliband is, don’t undermine the whole of your national strategy by allowing this major airport expansion to go ahead,” he said.“Don’t allow the whole of your carbon plan to be completely undermined by allowing the new Rosebank oilfield. They’re failing to focus on energy efficiency, how we insulate people’s homes to bring bills down, you’ve got to look at energy reduction as well as renewables if we’re going to deliver a green future.“And in terms of nature, they’re actively opposing the nature restoration agenda with this damaging suggestion that that economic success and nature are somehow at loggerheads. So that’s what’s led environmental campaigners like George Monbiot to increasingly suggest that Labour may be even worse on the environment than the Conservatives were.”

A Story About Salmon That Almost Had a Happy Ending

How tribal leaders, commercial fisherman and a few small environmental groups won an uphill campaign against dams.

Completion of the world’s largest dam removal project — which demolished four Klamath River hydroelectric dams on both sides of the California-Oregon border — has been celebrated as a monumental achievement, signaling the emerging political power of Native American tribes and the river-protection movement.True enough. It is fortunate that the project was approved in 2022 and completed last October, before the environmentally hostile Trump administration could interfere, and it is a reminder that committed, persistent campaigning for worthy environmental goals can sometimes overcome even the most formidable obstacles.How tribal leaders, commercial fisherman and a few modestly sized environmental groups won an uphill campaign to dismantle the dams is a serpentine, setback-studded saga worthy of inclusion in a collection of inspirational tales. The number of dams, their collective height (400 feet⁠⁠) and the extent of potential river habitat that has been reopened to salmon (420 miles⁠⁠) are all unprecedented.⁠The event is a crucial turning point, marking an end to efforts to harness the Klamath’s overexploited waterways to generate still more economic productivity, and at last addressing the basin’s many environmental problems by subtracting technology instead of adding it, by respecting nature instead of trying to overcome it. It’s an acknowledgment that dams have lifetimes, like everything else, and that their value in hydropower and irrigated water often ends up being dwarfed by their enormous environmental and social costs.

How nature organizes itself, from brain cells to ecosystems

McGovern Institute researchers develop a mathematical model to help define how modularity occurs in the brain — and across nature.

Look around, and you’ll see it everywhere: the way trees form branches, the way cities divide into neighborhoods, the way the brain organizes into regions. Nature loves modularity — a limited number of self-contained units that combine in different ways to perform many functions. But how does this organization arise? Does it follow a detailed genetic blueprint, or can these structures emerge on their own?A new study from MIT Professor Ila Fiete suggests a surprising answer.In findings published Feb. 18 in Nature, Fiete, an associate investigator in the McGovern Institute for Brain Research and director of the K. Lisa Yang Integrative Computational Neuroscience (ICoN) Center at MIT, reports that a mathematical model called peak selection can explain how modules emerge without strict genetic instructions. Her team’s findings, which apply to brain systems and ecosystems, help explain how modularity occurs across nature, no matter the scale.Joining two big ideas“Scientists have debated how modular structures form. One hypothesis suggests that various genes are turned on at different locations to begin or end a structure. This explains how insect embryos develop body segments, with genes turning on or off at specific concentrations of a smooth chemical gradient in the insect egg,” says Fiete, who is the senior author of the paper. Mikail Khona PhD '25, a former graduate student and K. Lisa Yang ICoN Center graduate fellow, and postdoc Sarthak Chandra also led the study.Another idea, inspired by mathematician Alan Turing, suggests that a structure could emerge from competition — small-scale interactions can create repeating patterns, like the spots on a cheetah or the ripples in sand dunes.Both ideas work well in some cases, but fail in others. The new research suggests that nature need not pick one approach over the other. The authors propose a simple mathematical principle called peak selection, showing that when a smooth gradient is paired with local interactions that are competitive, modular structures emerge naturally. “In this way, biological systems can organize themselves into sharp modules without detailed top-down instruction,” says Chandra.Modular systems in the brainThe researchers tested their idea on grid cells, which play a critical role in spatial navigation as well as the storage of episodic memories. Grid cells fire in a repeating triangular pattern as animals move through space, but they don’t all work at the same scale — they are organized into distinct modules, each responsible for mapping space at slightly different resolutions.No one knows how these modules form, but Fiete’s model shows that gradual variations in cellular properties along one dimension in the brain, combined with local neural interactions, could explain the entire structure. The grid cells naturally sort themselves into distinct groups with clear boundaries, without external maps or genetic programs telling them where to go. “Our work explains how grid cell modules could emerge. The explanation tips the balance toward the possibility of self-organization. It predicts that there might be no gene or intrinsic cell property that jumps when the grid cell scale jumps to another module,” notes Khona.Modular systems in natureThe same principle applies beyond neuroscience. Imagine a landscape where temperatures and rainfall vary gradually over a space. You might expect species to be spread, and also to vary, smoothly over this region. But in reality, ecosystems often form species clusters with sharp boundaries — distinct ecological “neighborhoods” that don’t overlap.Fiete’s study suggests why: local competition, cooperation, and predation between species interact with the global environmental gradients to create natural separations, even when the underlying conditions change gradually. This phenomenon can be explained using peak selection — and suggests that the same principle that shapes brain circuits could also be at play in forests and oceans.A self-organizing worldOne of the researchers’ most striking findings is that modularity in these systems is remarkably robust. Change the size of the system, and the number of modules stays the same — they just scale up or down. That means a mouse brain and a human brain could use the same fundamental rules to form their navigation circuits, just at different sizes.The model also makes testable predictions. If it’s correct, grid cell modules should follow simple spacing ratios. In ecosystems, species distributions should form distinct clusters even without sharp environmental shifts.Fiete notes that their work adds another conceptual framework to biology. “Peak selection can inform future experiments, not only in grid cell research but across developmental biology.”

From polar bears to polar vortex: How Columbia Sportswear uses nature to protect us from it

I’m standing on a corner in Reykjavík, the most flagrantly fragrantly delicious cinnamon roll I have ever had in my hand, and I am pouring sweat. It’s not because I worked hard to get this blissful brauð; it’s a leisurely 10-minute walk from my hotel. It’s not because it’s unseasonably warm; it’s Iceland in late […] The post From polar bears to polar vortex: How Columbia Sportswear uses nature to protect us from it appeared first on Popular Science.

I’m standing on a corner in Reykjavík, the most flagrantly fragrantly delicious cinnamon roll I have ever had in my hand, and I am pouring sweat. It’s not because I worked hard to get this blissful brauð; it’s a leisurely 10-minute walk from my hotel. It’s not because it’s unseasonably warm; it’s Iceland in late September and a brisk 40 degrees Fahrenheit. It’s because I’m wearing Columbia Sportswear Omni-Heat Infinity baselayers, and I have underestimated their insulating capacities—a mistake I will not make twice. It’s a mistake I shouldn’t have made at all. I spent several days prior testing out breathable membranes and thermal-reflective tech. Columbia’s gold metallic foil—introduced in 2021—helped insulate Intuitive Machines’ lunar lander when it was sent to the actual Moon in February 2024 (and when it launched again in 2025). In space, nobody can hear you sweat, but I’m walking through landscapes that only resemble Mars. And I’m audibly panting. I’ve trudged across the Solheimajokull glacier and been told that Omni-Heat Infinity would be a bit extra for those circumstances, so why I thought I needed it for a casual city stroll, well, I’m feeling the heat from that … I’m taking the heat for that. I packed Omni-Heat Infinity in case temperatures plunged below freezing. I should have stuck with what I’m actually in Iceland to learn about: Omni-Heat Arctic, Columbia Sportswear’s latest insulation system developed through research on polar bear pelts and demonstrated on less carb-focused, more high-output adventures. And what better place to test fabrics than where weather is constantly in flux. Iceland is a land of layers—both wandered and worn. On the Mid-Atlantic Ridge, where the Eurasian and North American plates slowly separate, the country is resigned to be redesigned as the Earth shifts and strains. But because a place is cold doesn’t mean it is unkind. A close-knit society on an unraveling rock, the Iceland I experience is a warm, self-reliant culture that demands warm, resilient clothes. I’ve only been in the country a few hours before I see a new road being freshly graded on top of what looks like last week’s lava. I’ve only been in the country a few more hours before it rains, shines, pours, and then the clouds part. Over the course of one day I’ll be doused winding behind the wind-whipped waterfalls, snake between surging sneaker waves, then scramble up the ashy veins of ice ridges. For every hour that’s brooding and bleak along the black sand coastline, there will be one that’s calm and bright beside thermal rivers. Hiking through the Reykjadalur Valley, we meet Skylar, who is backpacking solo through Europe and proudly shows off his one constant companion: a Columbia Sportswear flannel. Tranquility. Volatility. “If you don’t like the weather, wait five minutes” is a fitting expression and apt alert that you should always approach travel in Iceland with all manner of apparel handy. It’s a saying you’re just as likely to hear in Beaverton, Oregon, home to the Columbia Sportswear Company. Field-testing in Iceland is a first for our host, Director of Communications Andy Nordhoff, but this type of terrain isn’t foreign. Oregon may not be constantly altered by tectonic tension the way Iceland is, but it’s no stranger to maritime influences and geothermal forces. It’s a dramatic backdrop shaped by the slow grind of time and upheaval—weathered smooth in places, rough in others. It’s a landscape that has shaped Columbia since the company was formed in 1938. What started as a hat company is now one tough mother of an outfitter producing apparel and accessories for challenging environments.   And if there’s one thing folks from Oregon and Iceland know, it’s that there’s nothing worse than standing in a coat that has you remembering rather than feeling what it’s like to be warm or dry. To be present in adventures, you can’t be worrying about your clothes. A majority of activities in Iceland—from exploratory tourism to olfactory art collectives—are anchored in cultural reverence for natural resources and capturing the rejuvenating aura of the outdoors. And in a way, that’s the concept behind Omni-Heat Arctic, a solar-capture system. But before I found myself wrapped up in a fleece appreciating untamed beauty, Columbia’s in-house scientists spent years wrapped up in how nature solved the problem of thriving at extremes. Speaking from the Columbia campus, Dr. Haskell Beckham, vice president of innovation, explains how the company set out to “have the warmest jacket without the weight of a giant, damp puffer.” A puffer is, in the most basic terms, a bunch of chopped-up material stuffed in fabric. There’s down, there’s synthetic insulation, but it’s no matter what it’s operating with trapped air, which is low thermal conductivity. Still, humans constantly radiate heat, so the silver metallic Omni-Heat lining was introduced in 2010 to block that loss and reflect it back. Fast forward to 2021, and Omni-Heat Infinity introduced more surface coverage without impacting breathability, now with gold dots to tell the difference. Either way, they stood up to accelerated abrasion testing and real-world comfort testimonials. Plus the off-world partnerships with Intuitive Machines, who spoke the same language of thermal emissivity and solar reflectivity. So, having successfully applied materials science to space, the Columbia lab started thinking about icons of the most extreme environments on Earth. And Arctic inhabitants quickly came up. Digging into scientific literature about polar bears, however, revealed gaps in the understanding of how they survive. So Beckham knew he had to get his hands on a polar bear pelt. After trying the Oregon Zoo, Beckham followed a suggestion to contact the Burke Museum of Natural History at the University of Washington in Seattle. It turned out they did have a pelt that he could check out, like a library book, and he brought it back to the Portland area where it was studied for a year—placed in environmental chambers to measure how it reacted under a solar simulator at various watts per meter squared to mimic what it might see in a cold, yet sunny environment. And that’s when the Columbia team was able to shine some light on how polar pelts absorb light. “We discovered that the fur itself is actually translucent, but not transparent,” explains Beckham. “This lets a degree of solar energy transmission through the fur. And the bear’s skin is pigmented, which helps convert solar energy into heat—just like a black T-shirt in a warm environment feels warmer than a white T-shirt, which reflects solar radiation. With this system the pelt harvested solar energy and converts it to heat, so we set about creating materials and material stacks that have the same effect, which is partially about color and partially about density.” The end result, Omni-Heat Arctic, applies this discovery with thinner outer layers that allow sunlight to penetrate to the insulation (the equivalent of the underfur) and be converted closer to the body. However, unbroken black fabrics wouldn’t work, as the heat collects at the surface and is lost to the environment. It was imperative the solar radiation bypass the shell, go through the insulation, and be absorbed in a lining. For the Arctic Crest Down Jacket, the Columbia lab finally settled on a lining patterned with triangles and dots. Multi-layered engineering allowed the material to have a layer of metal topped with a coating featuring a black pigment. That black coating absorbs the solar radiation and converts it to heat, which is then conducted toward the body, while also protecting that heat from dissipating into the cold. And the team knew they nailed it when beta testers made unprompted comments about how it felt like the warmth amplified after the sun comes out, despite the external temperature.        “It’s a solar-boosted heat … like a biological greenhouse effect,” says Beckham. “That’s why the pattern on the puffer resembles a geodesic dome. On top of that, it’s a warmer jacket even when there’s no sunshine, thanks to how we engineer materials. “The fleece works a bit differently since they don’t have that special low E [low emissivity] coating, but [the high pile and black yarn lining] do work in that way a pelt naturally works.” As straightforward as all that sounds, Beckham’s research produced insight that challenged conventional wisdom, showing it’s not as simple as sunlight transferred through fur onto skin equals warmth. The fur density varies across the pelt, and as little as 3.5 percent of the light sometimes reaches the skin. So, an open question still remains about why the polar bear’s skin is black and what part it versus the fur truly plays in thermal regulation.  This, in a way, makes Omni-Heart Arctic an evolution, even an improvement on the natural means of solar transference. Confirmed by heat flux sensors, control of insulation, shell fabric/coating, lining, and moisture-resistant overlays allowed for garments with up to three times heat retention plus performance-oriented attributes. Core areas needing thicker covering and other areas needing flexibility and breathability can be targeted, while selectively absorbing sunlight promotes warmth without harmful exposure to UV.  Before this trip, my perspective on polar bears boiled down to “If it’s brown, lay down; if it’s black, fight back; if it’s white, say goodnight.” Now, I can appreciate what these creatures and Columbia Sportswear have done to address my mammalian shortcomings. Of course, when you think of a polar bear soaking up the Arctic sun, there’s a good chance you imagine it’s floating on an iceberg. While we didn’t go that far to test our textiles, we did take a sizable amount of moisture into consideration.  The Seljalandsfoss and Skogafoss waterfalls feel like veils between worlds—permeable but formidable. Piercing the multiverse requires preparation, however, and Columbia made sure we were ready with the OutDry Extreme Wyldwood shell jacket and pants. Thrown over the zip-up fleece, OutDry Extreme provided an impervious barrier without forming a moist bubble. With the hydrophobic film-like membrane laminated on the exterior (as opposed to the interior, topped by DWR-coated fabric), I didn’t worry about wet out or wet within. This orientation enhances breathability, allowing the interior fabric to wick perspiration away and more evenly distribute moisture vapor movement so no area gets overloaded. And as someone who constantly runs hot, I can vouch for its effectiveness. The Konos TRS OutDry Mid shoe kept my feet equally dry, stable, and cushioned throughout trail and town (and they remain my rainy day sneaker boots). Having a successful solution doesn’t mean Beckham and his team aren’t looking at new bio-inspired emulations that can improve outdoor apparel, however. The water-repellent properties of the lotus leaf are of interest, as the plant’s microstructure enables water droplets to bead up and roll off effortlessly. This could lead to durable, chemical-free, water-resistant gear. And the structural color of butterfly wings, where microscopic structures rather than pigments create hues, could lead to vivid, long-lasting color without dyes—another sustainable solution. From the 3D printers and swatch prototypes in their fab lab to the computational modeling that allows them to go through infinite combinations of inspirations and materials, the Columbia Sportswear scientists pursue innovation and efficiency.   I’ve now lived in the Arctic Crest Down Jacket and Arctic Crest Sherpa Fleece from one shoulder season to the next, trudging through the most brutally cold winter in a decade. Soon, it will be time to hang them up in favor of windbreakers and lightweight rain shells. In the not-so-distant future, Columbia Sportswear will have cooling technologies to reveal. But the polar vortex surged southward again as I started outlining this piece. Despite the spring-like weather that followed, early-morning hiking and biking isn’t exactly balmy yet. And there are always new latitudes to explore with the right daypack. So, as long as there’s even a hint of crispness or clouds in the years to come, I’m happy to bundle up in biomimicry to help me grin and, well, bear it, warm as a fresh cinnamon roll. The post From polar bears to polar vortex: How Columbia Sportswear uses nature to protect us from it appeared first on Popular Science.

Even Ground Squirrels Got In on the Vole Feast Last Summer

For the first time, scientists documented concerted carnivory by California ground squirrels. But why were there so many voles? The post Even Ground Squirrels Got In on the Vole Feast Last Summer appeared first on Bay Nature.

By last summer, University of Wisconsin–Eau Claire professor Jennifer Elaine Smith had been studying California ground squirrels at Briones Regional Park for twelve years. There wasn’t much these rodents could do that could surprise her.  Then her team saw a ground squirrel stalk, hunt, and eat a California vole. It wasn’t a fluke, like some weirdly motivated or superintelligent squirrel. Because, as the researchers found, the squirrels kept doing it. Again and again. They weren’t sit-and-wait-type predators, but instead chased down the voles over short stretches of dirt. The research team documented 27 individual squirrels hunting voles that summer. “I could barely believe my eyes,” says Sonja Wild, a postdoctoral research fellow in the UC Davis Environmental Science and Policy department who co-authored a paper in the Journal of Ethology on the unusual phenomenon. “From then, we saw that behavior almost every day. Once we started looking, we saw it everywhere.” A California ground squirrel on the move with its unusual prey: a California vole. Normally, ground squirrels eat a mostly plant-forward diet. (Sonja Wild/UC Davis)It was easy to see what was triggering it: there were just so many voles around. “This was shocking,” says Smith, a University of Wisconsin-Eau Claire professor who studies social mammals and lead-authored the paper, which was published in December last year. “We had never seen this behavior before.”  California ground squirrels (Otospermophilus beecheyi), on most days, have a plant-forward diet. They have also been known to eat meat such as bird eggs, hatchlings, insects, or each other on occasion—but this is the first time in nature that they had ever been documented hunting and eating California voles. “The widespread nature of vole hunting in our population fundamentally changes our understanding of this primarily granivorous species, suggesting that they are considerably more flexible in their diet than previously assumed,” the researchers wrote. California voles (Microtus californicus) are a burrowing rodent species that range from southern Oregon down to Baja California—sometimes living (dangerously?) in ground squirrel burrows. They are ubiquitous, but since they live underground, I usually only see a handful of these rodents every year.  That all changed last year. Female voles can have back-to-back litters—every 21 days—if conditions are right. Just imagine. (Vishal Subramanyan)A heck of a lot of voles In May, I was hiking in Sycamore Grove Park, a regional preserve in Livermore that I’ve been visiting for over seven years. As a wildlife photographer, I spend a lot of time in nature: being still and quiet, watching for animals. This time, from the start, I saw dozens of these tiny rodents running all over the trails. I’d only seen a couple of voles in this park over the years. I saw more of them in a few minutes than I had over the past several years. Throughout the course of my hike, I counted over 100 voles. It was a photographer’s dream. I hunched down and took dozens of photos as the voles scurried through fields, climbed on stalks, and ran in and out of their burrows. It appeared Northern California was in the midst of a vole population boom. Reports emerged of huge surges in their numbers, from San Francisco to Pleasanton to the El Dorado Hills, east of Sacramento. Smith’s team, crunching numbers from the community science platform iNaturalist, reported people logged seven times as many vole sightings in California as the average over the past decade. Livermore, like Briones Regional Park, was crawling with California voles last summer. (Vishal Subramanyan)Booms like this have occurred in the past. Just like their more famous cousins the lemmings, vole populations sometimes just go through the roof—reaching densities of up to 5,000 animals per acre. To humans, these booms may seem random. Vole populations typically cycle up and down over periods of three or four years, Smith says, but this was the biggest boom she saw over twelve years of study.  One thing that’s clear: Peak Vole is achieved by female voles reproducing at much higher rates than usual, according to Phoebe Edwards. She studied meadow vole population cycles for her Ph.D. thesis and is now an assistant professor of ecology, evolution, and organismal biology at Iowa State University. “As they’re increasing from a low population density, the females that are sexually mature are having lots of litters rapidly, back to back,” Edwards says. “They can even become pregnant once they’ve just given birth, and not all mammals can do that.” Voles can give birth to new litters every 21 days, she says. At the boom’s peak, birth rates slow. What sets off such industrious behavior? Generally, Edwards says, it’s because an opportunity has arisen: there’s more food around (possibly because of the climate changing), or fewer predators, or “changes to landscape use where voles are colonizing new kinds of habitats that weren’t really suited to them before,” said Dr. Edwards. Everybody likes eating voles The ground squirrels, like many, took advantage of the situation. Over the summer of 2024, researchers observed them hunting voles on 74 occasions over just 18 days of fieldwork. Of these, 31 involved active hunting, with squirrels stalking through tall grass or chasing voles across open dirt. And the hunters were quite successful—17 of the 31 documented attempts (55 percent) resulted in a kill.  Sometimes, squirrels tolerated other squirrels grabbing their killed voles. But occasionally the researchers saw squirrels fighting over their prizes. That made sense, they wrote, because “the energy contained in a single vole far outweighs that of more common food items, such as seeds or grasses.”  Population booms of small mammals like voles impact whole ecosystems, affecting predators and other animals. A slew of animals prey on voles, as Smith and team noted in their paper—“hawks, owls, egrets, long-tailed weasels, coyotes, skunks, mountain lions, and garter snakes”—all of which likely had more to eat. Burrowing rodents like voles are often ecosystem engineers, too, creating tunnels that other animals use. So more voles could also mean more habitat for those species. But these booms don’t last forever—so as vole populations crash, predators may be once again forced to turn to other prey, and small animals will have fewer places to live.  While the vole boom was a boon for animals with a taste for rodents, it touched human lives a bit differently. Grape grower Dane Stark, who runs Page Mill Winery in Livermore, noticed one summer day that some unknown vandal had nibbled a ring out of the bark on many of his youngest vines. He waited and watched, and quickly learned that the culprits were voles. They got to nearly all his vines. “I’ve been growing grapes for twenty years, and this is the first time I’ve ever noticed something like this,” Stark says. He hoped that the surge in vole numbers would bring in more predators to help control their exploding populations. Researchers documented last summer’s sharp spike in iNaturalist observations of California voles in their paper in the Journal of Ethology. (Courtesy of the authors)Have we passed Peak Vole?  It’s hard to know when or if the vole population boom is over. It would likely require an intensive field survey to get an accurate idea of their numbers. However, on my recent hikes this winter, I’ve observed far fewer voles compared to last summer. Community science reports on platforms like iNaturalist, which were essential in recording the vole boom last year, may also help understand the timing of the boom’s end.  Bobcats were among those that likely cashed in on a surfeit of voles last summer, along with “hawks, owls, egrets, long-tailed weasels, coyotes, skunks, mountain lions, and garter snakes,” according to researchers. (Vishal Subramanyan)The boom also raises other ecological questions, such as whether California ground squirrels learn hunting strategies socially or if it is a genetic predisposition. Wild and Smith are also interested in disease implications of the novel squirrel–vole interaction. “Parasites might be shared between voles and squirrels,” says Smith. “Future research will reveal the extent to which these interactions have positive or potentially negative consequences for ground squirrel populations.”  I’ll remember it fondly, as a wildlife photographer, given the abundance of photo opportunities the voles gave me. One evening, at a local park in Fremont. Down on the ground, voles were scampering across the fields. I watched as a bobcat quietly stalked prey alongside the trail. After patiently waiting for a few minutes, the bobcat pounced, grabbing one of the many voles that scattered these fields. It immediately took the vole and started trotting towards the cover, disappearing over the ridge as the sun set. In a prey boom, the mandate is the same for photographers as for bobcats: strike while it’s hot.  VIDEO A video compilation of ground squirrels hunting. Note: this contains some graphic imagery. (Sonja Wild, UC Davis)

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