FLORIDA KEYS — Health experts plan to release 750 million genetically modified mosquitoes in the Florida Keys to reduce local populations of disease-carrying mosquitoes, according to local news reports.

CNN reports that the Florida Keys Mosquito Control District currently budgets more than $1 million a year to combat the Aedes aegypti mosquito. The invasive species can spread deadly diseases like Dengue fever and the Zika virus.

Biotech company Oxitec designed the modified pests, called OX5034, to produce female offspring that die in the larval stage. In lab testing, just 3 percent of female offspring survived to adulthood, and these were too feeble to reproduce.

Only female mosquitoes bite humans and thus transmit deadly diseases, the BBC reports.

For the Florida Keys program, Oxitec genetically engineered male Aedes aegypti to carry a lethal gene that should prevent their female offspring from producing an essential protein, thus killing them before they reach biting age.

Environmental groups have warned of unforeseen outcomes. Between 2013 and 2015 Oxitec released millions of genetically engineered male mosquitoes in Jacobina, Brazil. Some of their female offspring survived long enough to reproduce.

Researchers from Yale University say the local population is now likely more resilient since the population has mixed with strains from Cuba and Mexico that were crossed together to create genetically modified males.