Fighting fire with... flies?

Experts using one exotic to help control another 

Charlotte Sun
Aug. 15, 2008

By NEIL HUGHES
Staff Writer

It sounds like a creature straight out of a horror movie, and it may be in your backyard.

The South American phorid fly could have been the inspiration for James Cameron’s 1979 science fiction classic, “Alien.” The bug lays eggs on the underside of its prey, and when the larvae hatch, they burrow inside the body of their still-alive host up into its head.

Once inside the head, the larvae eat its contents. Hence the scientific name Pseudacteon, or ant-decapitating fly.

Eventually a fly, one smaller than Lincoln’s nose on a penny, emerges from the corpse of its prey: an empty-headed fire ant.

Perhaps it’s no coincidence that phorid rhymes with horrid. And yet scientists in Florida are actively releasing the creature throughout Florida.

That’s because the phorid fly, which poses no threats to humans, crops or native animals, is a natural competitor of the imported fire ant.

“Think of it as the perfect biological control,” said Ralph Mitchell, director and horticulture agent for the University of Florida Institute of Food and Agricultural Sciences extension in Charlotte County.

The fire ant is an exotic pest that has been wreaking havoc in the southern U.S. since the species arrived in Mobile, Ala., on trade ship in the 1930s.

The ants spread throughout the south through shipments of garden nursery stock. They have thrived ever since.

Most people already know the problems fire ants cause, thanks to their notorious, painful bite. The creatures also attack animals, cause agricultural problems, and can destroy electronic equipment.

Aside from human-made chemical pesticides or fire ant baits, there aren’t any real competitors for the fire ant in the U.S., said David Oi, research entomologist with the U.S. Department of Agriculture in Florida.

To curb the rampant population, experts have been breeding phorid flies in the laboratory and strategically releasing them into the wild for the last decade.

In the process, countless fire ants have been killed with what certainly sounds like a horrible death, courtesy of Mother Nature.

“They will act normally,” Oi said of an ant with phorid larvae inside of it. “Eventually, (the larvae) will develop in the head, grow in the head, and eat out the contents of the head.”

The phorid fly’s reproduction methods are apparently so frightening to fire ants that the fly’s mere presence causes the ants to become less aggressive. Mitchell called the impact a kind of natural “psychological warfare.”

“The ants know it is a problem, and so they’re on alert,” Mitchell said.

Though fire ants are prevalent, there are other ant breeds native to Florida. What’s to say that the phorid fly won’t move on to other types of ants?

Oi said that’s not a concern. A great deal of research went into the phorid fly before its introduction in fire ant problem areas began a decade ago.

“There’s a whole regulatory process that they have to go through and get approved before,” Oi said. “We test these things very thoroughly.”

And the fly won’t bite humans either, he said.

It’s unrealistic to expect that the phorid fly will completely eradicate the imported fire ant from the southern U.S. There are simply too many fire ants to kill them all.

But experts hope these biological controls – perfected by evolution and nature over millions of years – can make an impact.

“This is the only way to go once they’ve spread,” he said. “We have to look at some biologicals that will be self-sustaining and can take care of the population on its now. Hopefully we’ll see lower populations.”