Pictures: "Zombie" Ants Controlled, Decapitated by Flies

Next Step: Head Detached

Photograph courtesy Sanford D. Porter, USDA

Eventually the phorid fly maggot injected into an ant decapitates its host (pictured in a file photo) and use its hollowed-out head as a place to develop into a pupa, an intermediate stage between larva and adult fly.

Just before that, the maggot appears to control the ant's behavior, directing it to a moist, leafy place where it can emerge away from other ants that would attack.

"Not only is [the fly maggot] decapitating it, but it turns the ant into a zombie," said Sanford Porter, a research entomologist with the U.S. Department of Agriculture.

(See more ant photos in National Geographic magazine.)

To control a fire ant invasion in the southern U.S., scientists have been releasing phorid flies into ant-infested habitats for more than a decade. Recently, Texas scientists let loose a new species of fly in Texas, which will ideally work in concert with the existing phorid species to kill a greater number of the fire ants.

"It certainly adds to the diversity of the impact," Porter said.

Published May 14, 2009

Peeking Out

Photograph courtesy Sanford D. Porter, USDA

A phorid fly larva emerges from the empty head of its fire ant host (pictured in a file photo).

Fire ants first emigrated from Argentina to Mobile, Alabama, in the early 1930s—probably on an agricultural-produce boat. They later spread to Texas and are still widening their range.

There's a long history of efforts to remove the ants, including physical removal and pesticides. But introducing phorid flies, which do not attack native ants, may be the most promising method so far, experts say.

Published May 14, 2009

Ready to Go

Photograph courtesy Sanford D. Porter, USDA

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.

Published May 14, 2009

Cruising for Fresh Prey

Photograph courtesy Sanford D. Porter, USDA

Despite successes in controlling fire ant invasions with the predatory phorid fly (adult shown above in a file photo), it's unlikely that fire ants will be totally ousted from the southern United States, experts say.

"They were still talking about complete eradication back in the early to mid 1970s," said Donald Feener, an ant ecologist at the University of Utah. "You're not going to eradicate something that is that widespread and that abundant unless you have all-out chemical warfare."

Published May 14, 2009