Phorid Fly Squadrons Still Battling Fire Ants

The offspring of thousands of Brazilian parasitic flies, released last summer to wage war on fire ants, have survived the first generation. Many field-reared flies have been found attacking ants and laying eggs to start a second generation. Agricultural Research Service scientists released the pinhead-sized flies last July through October as part of an environmentally friendly effort to control imported fire ants. Fire ants infest millions of acres in the southern United States.

Because the Brazilian flies are natural enemies of fire ants in South America, ARS scientists brought the flies to this country. The scientists are hoping the flies will lower currently high fire ant densities to the levels normally found in South America.

The flies swoop down on the ants and pierce their outer cuticle, depositing an egg inside the ant. The egg hatches into a larva within a dayor two.The larva moves into the ant's head--used as a protective case--where it completes its development. Once mature, the cycle repeats.

Researchers at ARS' Center for Medical, Agricultural and Veterinary Entomology released the flies at three locations near Gainesville, Florida: Kanapaha Gardens, the University of Florida Dairy Farm, and along Hogtown Creek. When scientists last checked in January, they discovered flies still attacking fire ant mounds. ARS research entomologist Sanford Porter says this is a good sign, showing the flies can survive and may have permanently established themselves.

It will take about another yearor twoto determine how effectively the flies are controlling fire ant populations at test sites in Florida. The scientists plan to release more flies in several other states later this year.

Scientific contact: Sanford Porter, Center for Medical, Agricultural and Veterinary Entomology, Imported Fire Ant and Household Insects Research Unit, Gainesville, Fla., phone (352) 374-5914, fax (352) 374-5818, sdp@nervm.nerdc.ufl.edu.