Red Imported Fire Ants

Red Imported Fire Ants

Troy E. Coggins

Extension Agent, Agriculture

Red Imported Fire ants are becoming a major pest throughout Davidson County especially south of I-85. The first concern with this pest is the painful stings received when mounds are disturbed. If a person or animal step on a mound, the ants will rapidly and unnoticeably cover the foot and leg of the unsuspected victim. The attack is in unison with tens to hundreds of ants all biting at one time. This is when the pain begins. Pustule-like sores(tiny blisters – thus the name “fire ants”) form at each sting. Scratching will lead to infection and scarring. It is best to consult your medical professional for treatment. A very low percentage of people are highly allergic. If these folks are attacked by more than a few stray ants, go directly for emergency medical care or call 911 for urgent Emergency Medical Service response.

The best thing to do is avoid contact with fire ants by not stepping, sitting or falling onto one of their mounds. The mounds in clay soils are symmetrical and dome-shaped. Often times they are 6 to 10 inches tall and 12 to 18 inches in diameter. It is also good to realize that for every inch of above ground height there is 2 to 3 inches of mound below ground. For example if the mound is 7 inches tall, there will most likely be 18 inches of active mound below the ground.

If you suspect a mound of soil to be an imported fire ant mound, you should obtain a wooden stick that is at least 18 inches tall. Hold the stick at the tip top and quicklyinsert the stick into the mound no more than 3 inches deep. Let go of the stick ASAP! Stand back and watch. In a matter of seconds, the stick will be crawling with small brownish colored ants if it is indeed an active fire ant mound.

The obvious question is what to do if you have an active fire ant mound. This will depend on where the mound is located. If it is in a landscape setting with little possibility of unsuspected human or pet traffic,a slow acting bait treatment is the best approach. Fire ant baits are a mixture of an insecticide and a food that is attractive to fire ants. For most products coarse ground corn is the food portion.Worker ants will carry particles of the bait back to the mound and feed them to the "brood" (larvae or immature ants) and the queen. The workers may be active inside the mound for several weeks before the colony dies. Ant baits are slow acting but easy to apply and very effective. The active ingredients in ant baits are rapidly degraded by high temperature, high humidity and intense sunlight.

If you have a fire ant mound in a “high traffic area” such as a playground, walking trail or similar area where the possibility of unsuspected human or pet making contact with the mound is high, a mound drench may be the best option. Mound drenches are insecticides diluted with water that work as contact insecticides. To be effective, the drench must trickle down through the mound and contact most of the fire ants, thus they should die in less than 24 hours. Apply the drench at a rate of 1 gallon per 6 inches of mound diameter. For example, a12 inch diameter mound would receive 2 gallons of insecticide drench. You should also thoroughly wet the ground to a distance of about 2 feet around the mound. Best results are achieved when the temperature is 70 to 85 Degrees F. Often times the drench does not kill all the fire ants in a treated colony. The surviving ants will construct small mounds within 10 to 15 feet of the parent colony. It is important to search for new mounds and treat again in high traffic areas.

This brings up my next comment as to what you should not do. Do not use gasoline, diesel fuel or similar products as insecticides. Dousing a quart of gasoline on the mound will result in a very shallow treatment with a high survival rate and the constructing of new colonies. So instead of one mound you have polluted the environment and now have 3 or 4 fire ant mounds. A bad plan! I also get questions about using scalding hot water to treat fire ant mounds. My first response is, “How will you get 3 gallons of scalding hot water to the mound and poured at a slow enough rate that it will trickle through the entire mound without scalding yourself?” Here again, the most likely result will be 3 or 4 new additional mounds but at least hot water does not contaminate the soil and ground water.

For a list of effective pesticides you can contact the NC Cooperative Extension Center 336-242-2080 or ask your pesticide dealer to consult the 2008 NC Agricultural Chemicals Manual. Remember with any pesticide product, the label is the law. The label that comes with the product will “over ride” anything anyone, including myself, will tell you about application, use, storage, etc. of any registered pesticide product. As the user of the product, you are responsible for complying with the product label and will be held accountable accordingly.