Starting today, British biotech firm Oxitec will begin releasing genetically modified mosquitoes in Florida and soon in Texas.

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.