Phire ants and phorid phlies

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ine years after he began researching how a tiny Brazilian fly can frighten an entire mound of red imported fire ants into staying indoors, Larry Gilbert sees the flying parasites poised for American stardom.

Once confined to a small breeding greenhouse on the north shore of Town Lake, the flies which are small enough to fit under Lincoln's nose on the head of a penny have spread across almost 100,000 acres of Central Texas, including from the Lady Bird Johnson Wildflower Center in Southwest Austin to as far north as Cedar Park.

"We've had some progress," said Gilbert, a University of Texas professor of integrative biology, who set the flies loose in hopes of their spreading. "After years of effort, through heat waves and several droughts, suddenly last year they took off."

The flies kill the ants one at a time, which obviously could keep them from being the final fire ant solution for decades, but the mere presence of a single, hovering fly has been shown to so frighten an entire imported fire ant colony that it disrupts their foraging for food.

The female flies kill by hovering in front of worker ants, then diving down to inject their eggs between gaps in the ant's armor. The egg develops inside the ant, and the new fly kills by eating its way out of the ant's body, then flies off to lay some more eggs.

With the spread of the flies known scientifically as phorids, agricultural extension agents and ranchers elsewhere in the state are clamoring for their share. They want to slow down the rampaging ants that have ruined many a picnic and caused billions of dollars in damages from North Carolina to Texas since arriving as stowaways on ships from Brazil in the 1930s.

Gilbert does not expect the flies to singlehandedly vanquish the imported fire ants and leave the field to the less troublesome native fire ants. But he figures they have at least as good a chance as other proposed remedies, from toxic pesticides to a new ant-killing virus distantly related to those that cause the common cold, the discovery of which recently was announced in Florida.

-- paul (primrose@centex.net), December 31, 2004


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