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Fire Ant Mounds Popping Up After Recent Rains

Fire Ant Mounds Popping Up After Recent Rains

AUBURN, Alabama—Thanks to recent rains, fire ant mounds are popping up in lawns across the state. An Alabama Extension entomologist says what appear to be new mounds have been around for probably several months at least.

“Just because you don’t see fire ants doesn’t mean they aren’t there,” said Dr. Kathy Flanders, who is also an Auburn University entomology professor. “When it is hot and dry, colonies don’t build the high mounds we are all familiar with.

“But when the rains come, they resume mound building and that’s why they seem to pop up overnight.”

She adds that understanding fire ants, Solenopsis invicta is key to managing them. “Usually people work too hard, spend too much money and use too much chemical to control fire ants, but it’s really easy to control these things if you understand their biology.”

Fire Ant Colony Basics

fire antMost fire ants in Alabama live in highly territorial single-queen colonies which may produce on average about 40 mounds per acre. However, in some portions of Alabama, fire ants live in multiple-queen colonies which are more tolerant of each other and may produce in excess of 200 or even 300 mounds per acre. A colony contains around 300,000 worker ants.  The queen ant lays all eggs, and only queens can perform this function.

“When a queen is in full form and has worker ants to help her, a queen can lay up to a 1,000 eggs per day,” Flanders said.

The worker ants forage for food, build mounds and protect the queen. When a queen dies, the entire colony will die because there will be no replacements for older workers.

Managing Fire Ants with Baits

Flanders recommends homeowners use fire ant baits as their primary means of control.

Fire ant baits are small particles that contain both a soybean oil food attractant and active ingredient for ant control. Following the bait packaging instructions, homeowners should spread the bait over their entire lawn. The ants will pick up the bait and bring it back to the nest, passing it between colony members including the queen.

“With this method, you take advantage of the ants’ normal behavior because they will be foraging for food anyway,” Flanders said.

The bait method usually will control 90 percent of fire ant colonies. It is effective and inexpensive at $10 to $20 per acre. Flanders also said the bait is the safest method for children, pets and the environment.

Many people do not understand fire ant biology and try to control the insects using individual mound treatments. Treating individual mounds can be costly and may not offer good control.

First, not all colonies have a visible mound. This means that homeowners will miss treating some colonies.  Also, worker ants will often move the queen ant, eggs and larvae away from danger. Worker ants will move the colony if they perceive a threat to the queen or colony and reestablish in a different area. While individual mound treatments may kill worker ants, they are not as effective as the bait method in killing the queen.

“If we miss the queen, we haven’t controlled that colony,” Flanders said. “Once we kill the queen, we kill the colony.”

Try the Two-Step Method

Flanders said a two-step method that combines bait treatment of an area with spot treatment of nuisance colonies that move into the bait treated area is an effective control strategy.  Learn more here at www.aces.edu/go/752.

“I don’t want you to work too hard to control fire ants,” she said.  “I don’t want you to spend too much money, and I don’t want you to use too much insecticide.

“That’s why baits work for me.”

Information on products currently available to treat fire ants in Alabama can be found at http://www.aces.edu/pubs/docs/A/ANR-0175-A/ANR-0175-A.pdf.


Featured image by Scott Bauer, USDA Agricultural Research Service, Bugwood.org

Close up image  USDA APHIS PPQ – Imported Fire Ant Station, Bugwood.org

About Maggie Lawrence