Thanks to warming climates, two debilitating tropical diseases have taken hold in America’s southern shore. The first is dengue, commonly called “break-bone fever,” which infects more than 50 million people a year with muscle aches. Its counterpart, chikungunya, causes joint pain and agonizing contortions. Both are transmitted by mosquitoes, which have been driven northward into the Florida Keys. As insecticides have proven useless, a promising new plan involving genetically-modified mosquitoes may stop the scourge, but only if it can get approval from the public and the Food and Drug Administration first.   

The black, tiger-striped mosquitoes that spread the two diseases are called Aedes aegypti, and they are resistant to four of six insecticides designed to destroy them. If left unchecked, these blood-suckers could travel into the Florida mainland and onward throughout the continental U.S., potentially spreading deadly diseases through welts and bites. Since 2013, the Centers for Disease Control and Prevention has issued travel warnings for Americans venturing to the Caribbean for this very reason. The Keys’ communities have tried many preventative measures, including fumigating areas of standing water where the insects breed. But a British biotech company called Oxitec has its own plans to combat the insects: have the species destroy itself.

Oxitec has bred mutant mosquitoes that carry a genetic “kill switch.” When these insects mate with the native population, they drastically reduce the insect’s birthrate. The company inserted protein fragments from coral, cabbage, the herpes virus, and E.coli bacteria into the insects, which they call OX513A. The protein potpourri creates a lethal gene, which male mosquitoes pass down to their offspring. When a modified male mates with a regular female, this gene kills the fertilized eggs. Oxitec plans to have their insects overwhelm the mosquitoes in the Florida Keys and wipe out the population.

“This mosquito is Dr. Frankenstein’s monster, plain and simple,’’ Helen Wallace, a British environmentalist with the organization GeneWatch, told The New Yorker in 2012. “To open a box and let these man-made creatures fly free is a risk with dangers we haven’t even begun to contemplate.” But since 2012, Oxitec has used its mutants in several residential neighborhoods, and after releasing 3.3 million of them in the Cayman Islands, more than 96 percent of the native mosquitos were suppressed, the company said. The plan achieved similar success in a town in Brazil as well.

Critics argue that despite the programs’ successes in Brazil and the Cayman Islands, Oxitec did not properly inform residents nor obtain their consent. While Oxitec plans to only release male, non-biting mosquitoes, some females may sneak through during the sorting process. These females can and do bite, potentially inserting their modified DNA into people. So far, the firm has said that it has released more than 70 million mutant mosquitoes without receiving reports of  any side effects from mosquito bites. Still, more than 135,000 community members in the Florida Keys have signed a petition to prevent the operation. “I think the science is fine, they definitely can kill mosquitoes, but the GMO issue still sticks as something of a thorny issue for the general public,” Phil Lounibos, a Florida entomologist, said. The FDA has yet to determine if the experimental eradication will get the go-ahead in the U.S. Oxitec has already built a lab in the town of Marathon, Florida with strict safety regulations.

The company is doing its best to convince residents of the program’s safety. “One of the most effective ways of demonstrating that is to go with a big cage of males, stick your arm in there, and say, 'Look, they’re not biting.’” Andrew McKemey, Oxitec's head of field research, told Motherboard. Still, even with safety demonstrations, Florida Key residents like Marilyn Smith are wary. She told the AP that she was not persuaded by Oxitec’s efforts to fight mosquito with mosquito. “Why are we being used as the experiment, the guinea pigs, just to see what happens?” To her and her neighbors, deadly diseases are less scary than a bite from the unknown.