Released October 7, 2009

COLUMBIA, Mo. – Missouri has its first confirmed report of red imported fire ants, and residents of Missouri’s Bootheel should be on the lookout for fire-ant mounds on their property, said Richard Houseman, University of Missouri entomology professor and state Extension entomologist.

Houseman and Judy Grundler, an entomologist with the Missouri Department of Agriculture, confirmed that red imported fire ants built mounds in Kennett, Mo.

“The mounds have likely been there for a few months,” Houseman said. “The mounds contained alates – winged ants that are ready to fly out of the mound and start new mounds somewhere else in the area.”

The alates indicate that the mounds have been there long enough for the ants to mature and reproduce, he said. “Red imported fire ants will swarm year-round, whenever it’s above 70 degrees, and this mound may have had alates earlier in the summer when swarming is more likely.”

Red imported fire ants are an exotic species brought to the United States more than 50 years ago in soil used as ballast in cargo ships from South America. They have since spread throughout the southeastern United States, costing affected states billions of dollars annually.

The dark reddish-brown insects build mounds that can be up to a foot in diameter. Within the mounds, there are several sizes of worker ants and several queens.

These aggressive ants bite and sting humans, livestock and pets. While biting, they release a pheromone that triggers all of the ants to sting simultaneously. They can sting through clothing and release a venom that causes the burning sensation that gives fire ants their name. Pustules, or blisters, form on the skin after the sting. In rare cases, attacks can result in anaphylaxis or infection.

Officials are not sure of the source of the red imported fire ants discovered in Kennett, but Houseman said they could have arrived in the area with landscaping plants purchased in nearby states where fire ants are established, such as Arkansas or Tennessee.

A Kennett homeowner discovered the mounds in late September and contacted Mike Milam, MU agronomy specialist, who took samples to MU entomologists for identification. Like many people in southeast Missouri, the homeowner purchased landscaping plants in Tennessee in the spring to replace those damaged in last winter’s ice storm.

“We really don’t know how long they’ve been there,” Houseman said. “Because it’s a mature mound, the concern is that they could have released alates that may have established new mounds elsewhere in the city.”

The site in Kennett is the typical environment where ants build their mounds. Milam found these mounds within an 8-foot area of the homeowner’s backyard, near a water spigot and under and around paving stones.

“They like open, sunny areas where the vegetation has been removed or landscape has been disrupted, or in fields where the ground has been tilled,” Houseman said. “When they become established in urban, agricultural or natural settings, they have a major impact on what happens there. These impacts include health, economic and ecological threats to humans, livestock, crops and wildlife.”

People who suspect they may have fire ants should inspect their property for mounds. “They can knock off the top of any suspicious mound and see if the ants come rushing out aggressively,” Houseman said. “If the ants get on them, of course, they’ll be stung.”

Treatment

Milam and Houseman recommend a two-step treatment. First, saturate the mound and surrounding soil with a liquid insecticide. “This is high-volume and low-pressure, so it soaks deep into the mound and gets the queens,” Houseman said.

Follow the insecticide treatment with granular ant bait specially formulated for red imported fire ants. Use a hand-spreader to blanket the area immediately surrounding the mound.

“We want people to first take samples before treating the mound, and then we can confirm whether it is fire ants,” Milam said.

To collect a sample, fill a small vial with alcohol. Use a cotton ball lightly moistened with alcohol to dab the ants that come out of the disturbed mound. Put the cotton ball and attached ants into the vial.

Samples can be taken to local MU Extension centers or sent to the MU Plant Diagnostic Clinic for analysis. For more details on submitting samples, see http://soilplantlab.missouri.edu/plant/.

Because fire ants reproduce quickly, managing them requires a community-wide effort, Houseman said. “That’s what will need to be done in this area.”

Houseman and Milam, along with the Missouri Department of Agriculture and USDA, are developing programs to educate Missouri residents, farmers and community leaders on managing the pests.

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http://extension.missouri.edu/news/DisplayStory.aspx?N=540

Sources: Richard M. Houseman, 573-882-7181

Mike Milam, 573- 888-4722

Editor: Eileen Yager, 573-882-0604, yagere@umsystem.edu