UPDATE: Phorid Fly emerges from the head of the ant in this photo

About 40 days after the egg is deposited, the phorid fly larva develops into a pupa that more close resembles an adult phorid fly (shown in a file photo). Although the flies only kill a small fraction of ants this way, the ants seem to be so afraid of the flies that their mere presence prevents the ants from collecting food, said Donald Feener, an ant ecologist at the University of Utah.Such interruptions slowly reduce the rate at which new fire ant colonies form.
—Photograph courtesy Sanford Porter
Research EntomologistTelephone: (352) 374-5914Fax: (352) 374-5818
E-mail: sanford.porter@ars.usda.gov
http://www.ars.usda.gov/saa/cmave/ifahi/sdporter
http://www.ars.usda.gov/pandp/people/people.htm?personid=4484
Biography
Sanford Porter is employed as a Research Entomologist for the USDA's Agricultural Research Service in Gainesville, FL. His specialty is the behavior and ecology of fire ants. He is currently evaluating and releasing phorid decapitating flies as fire ant biocontrol agents in the United States. He discovered that these parasites decapitate fire ant workers and then pupate in their heads. He also found that the impact of these flies on fire ant populations has been sufficient to cause the evolution of several phorid-specific defense behaviors. In 1996, he spent seven months on an ARS fellowship in Brazil studying these flies and developing ways to rear them in the laboratory.