Thursday, April 15, 2010

Time to Treat for Fire Ants

Red imported fire ants, Solenopsis invicta Buren, are an invasive species that has infested over 360 million acres in the southern United States, and they are continuing to spread. Fire ants are aggressive ants and within seconds after being disturbed, will begin to bite and sting. The fire ant workers bite first and then sting repeatedly, since they have a smooth stinger. After the first sting, it can rotate its stinger and sting again, leaving a circular pattern of stings. Most people who are not highly allergic develop welts and pustules. Fire ant stings can be fatal to those who are severely allergic. Symptoms of a severe allergic reactions include excessive swelling, shortness of breath, and thickening of the tongue. Those who are severely allergic to fire ant stings should seek medical attention immediately.
The use of chemicals is needed to manage their populations, in order to allow the native ant species back into the landscape. Fire ant baits, drenches, dusts and contact granular insecticides may be applied to control fire ants. It is advised to treat the individual fire ant mounds directly if less than 5 mounds are found within a 1/4 acre or less than 20 mounds within 1 acre, since this is not considered an infestation. However, if more than 5 mounds are present within a ¼ acre or 20 mounds within an acre, then a fire ant bait or contact insecticide should be broadcasted over the entire infested area. Fire ant baits are made up of defatted corn grit covered with insecticide and soybean oil. Before broadcasting the fire ant bait, foraging activity should be assessed, by placing a potato chip or hot dog next to the mound. If fire ants find the chip or hot dog within twenty minutes, then it is a suitable time to broadcast the bait. Fire ants will typically actively forage when the soil surface temperature is between 70 and 90° F, which is between May and September. Fire ant baits should never be watered into the soil and they should not be applied if they smell rancid. On the other hand, contact granular insecticides can also be broadcasted over the entire infested area and need to be watered into the soil. Control using contact granular insecticide generally lasts for 6 to 12 months, depending on the active ingredient within the insecticide.
Both fire ant baits and contact insecticides can be broadcasted using a hand-held spreader for small areas or a Herd Seeder can be mounted onto a truck or ATV for larger areas.
For more information, please visit the fire ant webpage at

Aftermath of many fire ant stings!

Fire ants stinging in a circular pattern.