They have been rendered sterile in a Kentucky lab by a company called MosquitoMate.

The mosquitoes were left incapable of impregnating females, after being infused with a Wolbachia bacteria.

The plan is over six months to release six million of the bugs that don't bite, but have a healthy sex drive, and will mate with females whose eggs won't hatch.

"We would expect to see the mosquito population decline," said Dr. William Petrie, Miami's director of mosquito control.  "If it works really successfully, the population will crash."

The sterile mosquito release is aimed at preventing another Zika virus epidemic like one that two summers ago saw the air filled with planes spraying potentially toxic pesticide over wide areas.  MosquitoMate, that developed the sterile mosquitoes, says previous trials have seen big results in knocking out those that carry Zika.