A Billion Lab-Grown Mosquitos Are Being Released and People Are Freaking Out

Starting today, British biotech firm Oxitec will begin releasing genetically modified mosquitoes in Florida and soon in Texas.
Billboards in the Florida Keys warn of the upcoming release of genetically-modified mosquitos.
Billboards in the Florida Keys warn of the upcoming release of genetically-modified mosquitos. (Photo: Barry Wray)

On Thursday afternoon, six Florida Keys residents will walk out into their yards and set out aquamarine cardboard boxes filled with mosquito larvae. Then, water will be poured into the containers. For the next ten days, as the mosquitoes grow into adults, their neighbors will be waiting to see what happens next. 

That’s because these aren’t just any mosquitoes: These are genetically-modified organisms, known as the OX5034, and they were made in a laboratory in London. 


Under a two-year Experimental Use Permit approved by the EPA, the British biotech firm Oxitec has been green-lit to release over 1 billion genetically modified mosquitoes across 6,600 acres in Florida and Texas. 

For their pilot project, they’re focusing on the lower Florida Keys, where in the coming 12 weeks, they plan to release 144,000 non-biting male mosquitoes from six different locations—making this the first time ever that a genetically-engineered mosquito will be let out into an open ecosystem in the United States. 

Screen Shot 2021-04-29 at 11.16.23 AM.png

Pouring water into an Oxitec container filled with Aedes aegypti mosquitos larvae. (Source: Oxitec)

And because Florida mosquitoes are growing increasingly resistant to insecticide, the Florida Keys Mosquito Control District, which has a budget of a little over $14 million a year to kill off as many bloodsuckers as possible, have teamed up with the private firm to get rid of the deadliest animal on earth. 

Oxitec’s technology will target the Aedes aegypti mosquito, which can carry dengue fever, Zika virus, and yellow fever, diseases that have been relatively common, and deadly, in Florida.

In the last decade, more than 7,300 dengue cases were reported in the U.S., and while most were contracted outside the country, 71 were transmitted in Florida, according to the CDC. In the summer of 2016, 29 people got sick with Zika through local-mosquito-borne transmission. The agency believed that exposure to the virus came from within a six-block radius in Miami-Dade County, which forced the county to aerially spray the area with pesticide


"The Aedes aegypti mosquito makes up about 4 percent of the mosquito population in the Keys but is responsible for virtually all mosquito-borne diseases transmitted to humans," the Florida Keys Mosquito Control District wrote in a press release. 

Since only the female mosquitoes can bite and pass on disease, Oxitec’s genetically-modified male mosquitoes all carry a “self-limiting” gene that is released when they mate with wild, potentially-diseased female mosquitoes. The gene is then passed on to their offspring, causing female baby mosquitoes to die before they can reach adulthood. 

“The female offspring of these encounters cannot survive, and the population of Aedes aegypti is subsequently controlled,” the mosquito control district wrote.

Oxitec has been proposing to release GM-mosquitoes into the Florida Keys since 2011, and the project has long stirred suspicion among locals, environmentalists, and scientists. 

“I don’t trust this company and I can’t trust their technology,” says Mara Daly, a resident from Key Largo who's been following Oxitec’s plans for nine years.  

Untitled design (45).png

Local opposition to the Oxitec genetically-modified mosquito project making itself heard on local billboards. (Source: Barry Wray)

For Daly, it all started in 2012, when Oxitec introduced its project to the general public. 

“I wanted to get behind it. I really did. But from the beginning, something was off,” she told VICE News. “They were talking about a sterile insect that would still produce offspring. How was that possible? It just didn’t add up.” 


That same year, the Key West City Commission opposed Oxitec’s proposal. 

Then, in 2016, in a nonbinding referendum, residents of Key Haven––the community where the mosquitoes were supposed to be released––rejected a second proposal. But, in another countywide referendum, voters overwhelmingly supported the release. Ultimately, the Florida Keys Mosquito Control District approved the trial for the Keys, just not in Key Haven. 

Ever since then, residents at public meetings have raised fears they’re being used as “guinea pigs” and “laboratory rats.” Facebook groups like “GMO-Free USA” and “GMWatch” have been exploding with mistrust and concern from locals, including some who don’t seem to realize they voted in support of the project five years ago. 

But those opposed to the project aren’t necessarily anti-GMO. Many of them, like Daly, are skeptical about how the EPA approved this experiment, how the company monitored the results of its previous trials, and what the risks of this technology could be. 

“We want proper oversight, we want proof that absolutely nothing can go wrong,” Daly said. “Because if it does. we can’t just recall a flying insect, can we?” 

Daly’s biggest issue with the genetically modified insects is an apparent lack of independent evaluation—meaning testing done by those outside of federal agencies and the company itself—to ensure it's safe for both humans and the local ecosystems. 


“It comes down to one primary issue,” said Barry Wray, executive director of the Florida Keys Environmental Coalition, who opposes the release. “This technology has not been properly investigated by independent scientists.” 

“We are screaming for the science to be done properly so that we understand what the risks really are,” Wray said. “We just want to confirm it’s safe.”  

Screen Shot 2021-04-29 at 11.43.59 AM.png

Oxitec is also taking out billboards to educate the public on genetically-modified mosquitos. (Source: Oxitec)

Jennifer Kuzma, co-director of the Genetic Engineering and Society Center at North Carolina State University, insists she’s neither for nor against GMOs but argues there should have been a more independent, external scientific advisory panel to review Oxitec’s project.

“I think that it [the technology] can have benefits to reduce the Aedes aegypti and possibly disease in the future,” Kuzma says. "But my colleagues and I have some concerns about the process by which the decision was made at the federal level. One of the problems was that the risk assessment on the Oxitec mosquito was not published prior to the public comment period. So there wasn't an opportunity for independent scientific evaluation of the risk assessment.” 

“The second thing is that there wasn't anything in the peer-reviewed literature about this particular strain,” she said. “So it's hard to evaluate the claims of the effectiveness of the technology as well as the potential risks and benefits if there's nothing in the public peer-reviewed literature or scientific literature.”  


But Oxitec says they have all the proper approval necessary to go forward with this project—on top of the EPA’s approval and risk assessment, which determined the information that the company provided “to be adequate to support a finding of no unreasonable adverse effects to man and the environment during the proposed EUP.”  They’ve also gotten the go-ahead from an advisory board of the Centers for Disease Control and Prevention as well as the Florida Department of Agriculture and Consumer ServicesAnd Oxitec scientists assure there’s nothing to worry about: They’ve already released more than a billion bugs in Brazil and the Cayman Islands in similar trials—both of which the company claims were successful. 

According to Oxitec, the trial in the Brazilian city of Indaiatuba “found that Oxitec’s mosquito suppressed disease-carrying Aedes aegypti by up to 95 percent in urban, dengue-prone environments after just 13 weeks of treatment, as compared to untreated control sites in the same city.”

Despite Oxitec’s assurances that their earlier-generation genetically modified mosquitoes would be unable to reproduce in their Brazil trial, traces of the mutated insects were detected in the natural population of mosquitoes, according to research published in 2019

The researchers of this study also showed that while there was a dramatic reduction in the mosquito population for 18 months after the Oxitec mosquitoes were released, the population began to recover soon after. Finally, the scientists suggested that added genetic diversity between genetically modified mosquitoes and wild mosquitoes could result in a more robust species, a phenomenon known as “hybrid vigor.”

In response, Oxitec called the paper’s findings both misleading and speculative, and said that they dramaticized statements to create unfounded concerns. The company stated that their first generation GM-mosquitoes had proven to be safe, and their second generation were even safer and more effective. Ultimately, six of the study’s ten authors requested retraction of the publication.

But for locals like Barry Wray and Mara Daly, who see this as a fight to protect their families, their neighbors, and their environment from potential danger–they won’t rest until they feel more assured. Despite the fact that the adult male genetically-modified mosquitoes are due to hatch in early May—and once the water is poured into the boxes, nothing can stop them—they still want more clarity on the risk these insects pose to them, especially before the second, bigger Oxitec trial starts later this year.

“We’ve seen this before: There's no way we can foresee what will happen if we release these mosquitoes. What if they become stronger? What if they become deadlier? What if they’re resistant to antibiotic-bacteria? What if things don’t go according to plan?” Daly says. “Shouldn’t we be absolutely certain that we’re being as safe as possible?”

Follow Valerie Kipnis on Twitter.