After the heavy rains last week, fire ant mounds began popping up again. The month of May is an ideal time to treat fire ants with a bait product before it gets hot. Baits are relatively inexpensive, require little labor to apply, and are safe for both you and the environment. The biggest drawback of baits is that they cannot be used all year round. Instead, applications must be timed to periods when fire ants are actively looking for food.
The red imported fire ant, originally from South America, spread through Texas starting in the 1950s, 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, messing with our okra and making life miserable for everyone. Cost of damage and controls is in the hundreds of millions of dollars.
Agencies and universities involved in fire-ant research have learned much about their biology and behavior, tested many pesticide formulations and are researching 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.”
Since the fire ant is not a major pest in its native South America, researchers have looked for naturally occurring enemies in Brazil and other countries. Several potential natural enemies and pathogens have been identified and are being investigated to see if they will be useful in the fight against these stinging pests.
One natural enemy that has received attention is a tiny Brazilian phorid fly. This fly parasitizes fire ants by laying an egg on the ant, which hatches into a larva, which then lives in and consumes the contents of the ant’s head (obviously killing it). The greater benefit is that phorid flies alarm the worker ants, causing them 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. Native ant species are far less aggressive and harmful. So there’s a positive domino effect. Researchers emphasize that these parasites affect only the imported red fire ant, and not our native species.
As scientists learn more about their biology, genetics, reproduction 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 quarter-acre 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. There are several different brands of fire-ant bait, and several different ingredients in them, including organic ingredients. They contain minute amounts of slow-acting insecticides on granules attractive to foraging fire ants. Ants pick up the bait thinking it is food, and take 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 ant’s growth and development. Eventually the colony starves because no new worker ants are produced.
Always read and follow the application instructions on the label of the product you are using. Use a handheld spreader/seeder for baits that are applied at very low rates such as 1 to 5 pounds of product per acre. Use the push-type spreader for baits that are applied at higher volumes per acre (2 to 5 pounds per 5000 square feet).
For successful bait application,
n Apply baits when ants are foraging (looking for food). To tell if ants are active, place a small amount of food (hot dog slice, tuna can lid, or potato chip) in the yard. If ants gather within 30 minutes, it’s a good time to treat.
n Fire ants are most likely to forage for food when the soil temperature is between 70 and 90 degrees one inch deep.
n During the heat of summer, apply baits in the evening. If applied during the heat of the day, baits quickly lose their attractiveness. Also, ants do not forage much during hot summer days.
n Use only fresh bait, preferably from a new, unopened container. Once opened, baits should be used quickly. Opened containers may last only a few weeks. Unopened containers stay fresh for up to two years.
n Test baits for freshness before using. Sprinkle a small amount next to an active mound. If the bait is fresh, ants will begin removing it within 30 minutes.
n Apply baits when no rain is expected for at least eight hours. This reduces the risk of it being washed away.
The second step is to treat, after at least 24 hours, nuisance mounds posing threats to human activity. There are a large number of product options available to treat individual mounds, including organic products and faster-acting baits.
A leaflet called “The Texas Two-Step Method” is available through county Extension offices throughout the state. For much more information (including the leaflet 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 and Extension’s www.extension.org/fire_ants web site.
Always read and follow closely the directions provided on the product label before using any pesticide.
Keith Hansen is Smith County horticulturist with the Texas A&M AgriLife Extension Service. His web page is http://EastTexasGard ening.tamu.edu His blog is http://agri life.org/etg.