KEY WEST, Fla. (AP) — Millions of genetically modified mosquitoes could be released in the Florida Keys if British researchers win approval to use the bugs against two extremely painful viral diseases.

The Florida Keys Mosquito Control District is waiting to hear if the Food and Drug Administration will allow them to run an experiment in Key West to see if the modified bugs can suppress the population of Aedes aegypti mosquitoes, which spread dengue and chikungunya.

Mosquito controllers say they’re running out of options because most approved insecticides are no longer effective against Aedes aegypti.

The British company Oxitec has built a breeding lab in Marathon and hopes to release its mosquitoes this spring if approved by the Food and Drug Administration. But some residents are frightened at the thought of being bitten by genetically modified organisms.