Keith Hansen

Dry conditions during the summer and the absence of fire ant mounds may have you thinking that they are gone from your property. But, the hot, dry weather has driven these pests deeper in the soil where it is cooler and moister. But, these soaking rains from Gustav will stimulate mounds to pop up all over the place. The good news is that Fall is a very good time to treat for fire ants.

The red imported fire ant, originally from South America, spread through Texas starting in the 1950's, and now infests more than 80 million acres in the eastern two-thirds of the state, causing havoc to electrical and farm equipment, stinging and killing wildlife, and making life miserable for everyone. Cost of damage and controls is in the $100's of millions of dollars.

Agencies and universities involved in fire ant research have learned much about the biology and behavior of the species, tested many pesticide formulations, investigated and released promising biological control agents. However, there is still a long way to go before fire ants will be relegated to the status of "just another ant."

One method being recommended for urban areas heavily infested with fire ants is community-wide management, where neighborhoods are encouraged to treat for fire ants at the same time so the ants don't travel from yard to yard. In one recent report, a neighborhood in San Antonio reduced fire ant mounds in common areas by 98%. A similar study in Round Rock reported a reduction in pesticide treatment costs by 58%.

Since the fire ant is not a major pest in its native South America like it is in the United States, researchers have been investigating the naturally occurring enemies in Brazil and other countries that keep the ants in check. Several potential natural enemies and pathogens have been identified and these are being investigated to see if they will be useful components in the fight against fire ants.

One natural enemy which received a lot of attention is a tiny Brazilian phorid fly. This fly parasitizes fire ants by laying an egg on the ants which hatches into a larvae which lives in and consumes the contents of the ant's head (obviously killing it). The phorid fly basically stalks the worker ants to lay their eggs, which prompts the ants to hide. If they're hiding, they're not taking food back into the colony. That weakens the colony and also benefits native ant species, because there's more food for them. The native ant species are far less aggressive and harmful. So there's a positive domino effect.

Since 1999, researchers have been testing one species of the phorid fly which has been mass produced and experimentally released in several locations in Texas. Several established phorid fly populations have been documented, including one a few years ago year in north Texas near Denton, indicating the phorid fly has the potential to aid in the battle against fire ants.

Basic research is also being conducted on fire ants to learn "what makes them tick". As scientists learn more about their biology, genetics and chemistry, more tools will become available in the fight to provide long-term control.

Today, the 2-Step Method is recommended for providing up to a year's worth of control for areas where fire ant populations are heavy. This would describe property with greater than 20 mounds per acre (or about 4 to 5 mounds in an average urban yard). Where populations of fire ants are less abundant, the bait broadcast method is not recommended in order to conserve native ant species.

The first step involves broadcasting a bait product specifically designed for fire ants. Baits (there are several types and brands) contain minute amounts of slow-acting insecticides on granules attractive to foraging fire ants. Ants pick up the bait, taking it back to the colonies to feed to the developing brood or queens. Some baits are insect growth regulators, not actually killing the ants, but disrupting the ants growth and development. Eventually the colony starves out as no new worker ants are produced.

Keys to successful bait applications:

Apply baits when ants are foraging. To see if ants are active, place a small amount of suitable food (hot dog slice or potato chip) next to a mound. If ants begin removing the food within 30 minutes, it's a good time to treat.

If the bait is fresh, ants will begin removing it within 30 minutes.

The second step is to treat, after about one week, nuisance mounds posing threats to human activity. There is a large range of product options available to kill individual mounds, including organic products and the faster-acting baits. Always read the label on any pesticide product and carefully follow directions for mixing, application rate and disposal.

A leaflet called "The Texas Two-Step Method" is available through county Extension offices throughout the State. For much more information, (including the above brochure and others), on fire ant research, products, methods, organic and alternative control methods, and Spanish language publications, check out the Texas A&M's fire ant Web site at http://fireant.tamu.edu.

Keith Hansen
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