Fire Ant Control

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Fire ants are a nuisance in the home landscape. Mounds detract from the overall beauty of your area, plus fire ants can inflict a painful sting! Unfortunately, fire ants are in Lee County to stay, so homeowners with a problem will need to learn effective management strategies.

Red Imported Fire Ants (RIFA) were imported into the United States in the 1920s. The ants came from Brazil in infested soil used as cargo ship ballast. By 2003, all of Lee County was included in the NCDA quarantine area.

Fire ants are social, organized insects with differing classes (similar to honeybees). The queen ant lays eggs (up to 1,500 per day) her entire life, which can last seven years. The ants forage for food when temperatures are between 72 and 96 F, which correlates to the afternoon during spring and fall and the evening in the summer. Fire ants are not very active during the winter.

How do you know if you have fire ants and not another mound-building creature? Of course, if you have experienced the painful sting, you know! Sometimes the ants are not present, but a mound is. Fire ant mounds do not have an entrance hole – ants enter and exit from periphery tunnels. The ants vary in size, from 1/8 – 1/4 inch, depending on the class. Fire ants are unique in that they will run vertically up a stick (or leg) that penetrates the mound.

Most people want to eradicate fire ants from the landscape, which certainly would be nice. Eradication efforts were made in the 60s and 70s, but were unsuccessful. Eradication is an impossible goal due to a number of factors, so we are left to strive for the elimination of the problems caused by RIFA.

The decision to start a control program for fire ants is a long-term commitment. Failure to keep up with a program could actually result in more ants.

One option for control is to use mound drenches or powders. These insecticides work when the chemical comes in contact with the ant, so these treatments are effective at killing many worker ants, but often not the queen. If the queen survives, the colony survives.

Contact insecticides, whether they be powder, liquid concentrate, or granular, will need to be watered in with enough water to penetrate the mound. Follow all instructions on the label. Always treat an undisturbed mound for the treatment to be effective (I know many of you like to kick the mound and watch them die!).

Contact insecticides work quickly and are extremely useful when mounds appear in hazardous areas including playgrounds, walkways, and other places where human contact is likely. However, the quicker the treatment, the quicker the reinvasion.

The other treatment option is to use a bait product. Bait products consist of a pesticide adsorbed onto a corn grit. Baits are attractive to fire ants, and workers gather the bait particles to bring back to the mound. Then, the bait (and pesticide) are fed to other worker ants, the brood and the queen, effectively exposing all the ants to the chemical.

Baits work in one of two fashions: as a toxicant, meaning the chemical must be consumed, or as an insect growth regulator (IGR), meaning normal insect growth and development are disturbed. Toxicants work quicker than IGRs on average. While toxicants can provide maximum control in 2-4 weeks, IGRs often provide maximum control 2-6 months after application.

When using a bait, follow these steps:

  1. Use fresh bait from an unopened container less than 2 years old.
  1. Apply baits when the ground and grass are dry and when no rain is expected for 24 hours. (Never water a bait in!)
  1. Apply when worker ants are actively foraging. This can be determined by putting a piece of greasy food (a chip, popcorn, or hotdog) near the mound. Then check the food item in 30 minutes for activity. If ants are present, foraging is taking place.
  1. Treat individual mounds by sprinkling the recommended amount of product around the mound, up to 3 feet away. Do not disturb the mound while treating. Also, do not apply the bait product on top of the mound, since fire ants do not forage for food on the mound.

Although many Lee County residents battle with fire ants, many situations can be treated as individual mounds. Broadcast applications of a bait or a contact insecticide can be made if the area to be treated is large or there are 20 or more mounds to be treated.

For more information on controlling fire ants in the landscape, contact our center at 919-775-5624.

Amanda Bratcher is the Horticulture Agent for North Carolina Cooperative Extension in Lee County.