U.S. agriculture officials are releasing the last sterilized flies to fight a flesh-eating parasite in a Florida Keys wildlife refuge.
The U.S. Department of Agriculture has released about 190 million irradiated flies since September to stop screwworms from reaching Florida's mainland. The last release was Tuesday.
A screwworm infestation killed 135 endangered Key deer before the infections stopped in January.
USDA veterinarian Jack Shere told The Miami Herald the parasites were found on 13 islands in the Keys. The USDA spent up to $4 million to treat and monitor the isolated deer.
The USDA is comparing DNA from screwworms in the Keys to flies found in the Caribbean and South America to determine how the outbreak started. It is the first U.S. screwworm infestation in over 30 years.