Published 12:00 am Wednesday, December 2, 2009
My nephew was helping his Dad do some yard work one day. He sat down on the ground to take a breather. In a few minutes he began to feel painful stings on his legs and back. He ran into the house and immediately got into the shower. Only then was he able to detach his aggressors.
The culprits of all his pain were fire ants. He later had an allergic reaction to all the stings and had to receive medical attention.
The red fire ant is an imported pest that continues to expand its range in North Carolina and is showing up more and more in parts of Rowan County. It is little wonder that the fire ants are here, as the areas of Cabarrus, Stanley and the southern part of Iredell are in a quarantined zone.
The U. S. Department of Agriculture and the North Carolina Department of Agriculture & Consumer Services regulate the export of certain items that might carry ant infestations to other parts.
How did the fire ants get here?
The red fire ant is a native of southern Brazil. In North Carolina, fire ants are found throughout much of the eastern part of the state, along with isolated areas in our part of the Piedmont.
Because of the North Carolina mild winters and the increased residential and industrial development, fire ants were introduced through infested sod and nursery stock. Also, the ants expand naturally and steadily into new territory because of their high reproductive rate.
Adult fire ants are reddish to dark brown and can occur in five forms: minor workers about 1/8 inch long; major workers about 1/4 inch long; winged males and females, each about 1/3 inch long; and queens about 1/3 inch long. Fire ant mounds vary in size, usually in direct proportion to the size of the colony. For example, a mound that is 2 feet in diameter and 18 inches high may contain about 100,000 workers, several hundred winged adults and one queen.
Two aspects of fire ants infestations are particularly annoying: the unsightly mounds formed in lawns and yards and the painful stings received when mounds are disturbed. Within 24 hours after a person is stung, a pustule-like sore forms at each sting site, which usually itches intensively. Scratching the pustule may rupture the skin, leading to secondary infection and scarring. A small number of people, like my nephew, are highly allergic to fire ant stings and require immediate medical attention.
Fire ants aren’t limited to lawns. In some southern states, foraging ants have invaded private residences, offices and even nursing homes.
Fire ants are difficult to control. Individual mounds are best treated with a liquid drench of insecticide or an insecticidal bait. Mound drenches work as contact insecticides. It must trickle down through the mound and contact most of the fire ants. Follow all insecticide label directions.
Apply the drench at a rate of a gallon per 6 inches of mound diameter. Thoroughly wet the ground to a distance of 2 feet around the mound. Some ants may not be killed by the first treatment and will construct a small mound 10-15 feet away. Treat new mounds as they appear.
Baits can also be used to treat mounds. Baits are insecticides that have been mixed with something that will attract the ants, such as oil. Worker ants carry particles of baits back to their mound and feed the queen. Baits may take several weeks before the colony disappears.
People have tried non-chemical controls with only limited success. People have tried hot water, mechanical disruption and grits. Scientists have tried biological controls, including parasitic flies, fungi and other microorganisms. Most ants simply move elsewhere when disturbed.
There is no simple trick to fire ant control, but with a consistent control plan, you can at least protect your lawn and other vulnerable areas.
As with most insects, fire ants will be around here for a long time. We will have to learn how to deal with their annoyance.
Fire ants aren’t the bad guys all the time. They could be considered beneficial since they feed on many other insects that also can plague our lawns and landscapes.
James C. Cowden is director of the Rowan County Extension Service.