Colony of fire ants discovered in Beltsville Pest-control officials keep watch on infestation on grounds of USDA

January 18, 1998|By Ted Shelsby | Ted Shelsby,SUN STAFF

Fire ants, whose sometimes-fatal stings have tormented the South for nearly 70 years, have established a colony in Maryland.

zTC The ants have taken up residence along a concrete walkway at the U.S. Department of Agriculture's research center off U.S. 1 in Beltsville, and state pest-control officials are out to destroy the unwelcome invaders.

"Their sting is like putting a hot match on your arm," said David Williams, an entomologist with the USDA's fire ant research center in Gainesville, Fla.

He said the ants can kill young deer, cats and dogs. At least 50 people have died in recent years from allergic reactions to fire ant stings.

"But don't be alarmed," he advised Marylanders. "We think they can be easily taken out." The Beltsville infestation was discovered in late October.

"It is something we need to be vigilant about, but there is nothing for the general public to be alarmed about," said Robert Trumbule, a field inspector and entomologist with the Maryland Department of Agriculture.

Trumbule is leading the battle against the ants.

He said the underground colony is in an area where buried steam pipes heat the soil.

His initial attack involved spreading a bait treated with insecticide throughout the infested area, a section of lawn more than 10 yards across.

"They eat the bait and take it back to the nest to feed the others," Trumbule said. "It is passed throughout the colony. It is one of the most effective ways to treat ants."

In cold weather, Trumbule said, fire ants are not very active and usually remain under ground and out of sight.

Trumbule said the strategy is to keep an eye on the infestation until spring, when field workers will perform what the state pest-control officials call a delimiting survey, which is a search for traces of ants starting at the original site and expanding in larger and larger circles to determine the limits of the infestation.

Once the limit is determined, the soil is soaked with a chemical insecticide designed to kill survivors.

"We will continue to survey the area for another three years to make sure there are no more ants there," said Bart Smith, supervisor of the pest-control field operation of the state Agriculture Department.

No one is certain how the ants got here, but Trumbule said they probably hitched a ride on a shipment of nursery plants from the South several years ago when major landscaping work was being done at the research center.

"They have probably been here for several years," he said.

Williams said fire ants can't survive in very cold weather, and Maryland is on the fringe of their survival area.

Red fire ants, such as those in Beltsville, came to the United States in 1930 from South America aboard a shipload of lumber bound for Mobile, Ala., Williams said. They have since made their way to 11 states, from Texas to as far north as Virginia.

Pub Date: 1/18/98

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