June 25, 2019 - Those hot, sweltering summer days are rapidly approaching! With them come days spent at the pool or on the lake, cooling off with an ice-cold slice of watermelon, wiping sticky popsicle residue off of grinning faces, and… fire ants? It would be hard to find someone who does not know what it feels like to be an unsuspecting victim of an aimless fire ant attack.
This time of year, the heavy rains cause fire ant mounds to pop up overnight like magic. Simply stepping on or mowing over a mound to destroy it just isn’t enough. Like clockwork, worker ants rebuild a mound that has been destroyed in a seemingly spiteful manner. Often, the new mound is much larger than the original mound – sometimes reaching more than one foot tall. How can we combat such an invader? The red imported fire ant, originally from South America, spread through Texas starting in the 1950’s. According to Texas A&M AgriLife Extension, fire ants now infest more than 80 million acres in the eastern two-thirds of the state, wreaking havoc on electrical and farm equipment, stinging and killing wildlife, and messing with our crops. The cost of damage and controls is in the $100’s of millions of dollars.
Texas has 36.8 million acres of prime farmland, the most found in any state. In 2018, the value of Texas’ crop production was roughly $8.4 billion. Texas farmers invest a considerable amount of time and money preventing infestations by weeds and pests so that the highest quality commodities reach the consumer. Agricultural invasives, both plant and animal, also cost farmers by diminishing crop quality and limiting their choices of crop rotation cycles and other management practices.
Certain animal invasives, such as red imported fire ants, Africanized honeybees, and feral hogs, attack young livestock, resulting in severe losses to the ranching industry. According to the Texas A&M Fire Ant Research Project, it costs Texas ranchers $10 to $15 per acre per year to control fire ant populations in their pastureland.
In Texas, where extreme weather events are common, some biological invaders that have already been introduced to the state can expand their distribution through these natural phenomena. For example, fire ants disperse naturally by floating to new locations on floodwater, which is why we see fire ant mounds sprout after a heavy rain.
While fire ants cause disarray here, they are not a major pest in their native South America. There are preventative measures, such as baits and insecticides, that can be taken to protect your yard from a fire ant infestation, but what is a farmer supposed to do to rid his agricultural land of an invasion?
Researchers have been evaluating naturally occurring enemies of the fire ant in Brazil and other countries. Although several natural enemies and pathogens do exist, will they be useful in the fight against fire ants and is it wise to introduce a foreign species just to control another? One natural enemy which has received much attention is a tiny Brazilian phorid fly. This fly parasitizes fire ants by laying an egg on the ant which hatches into a larva, and then lives in and consumes the contents of the ant’s head (obviously killing it). This sounds worse than most of the Horror movies being advertised, but to what extent do we allow this foreign invasive species to terrorize our land and livestock?
Although they are small, fire ants are mighty in terms of the damage they can cause. Research continues to be conducted, both domestic and abroad, so that farmers and ranchers can feel some relief. Until a fool-proof exile method is discovered, the 2-Step Method is recommended by Texas A&M AgriLife Extension 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 ¼ acre urban yard).
Step 1 involves distributing a bait product specifically designed for fire ants. Baits (there are several different active ingredients and brands, including organic) contain finite 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. 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).
Step 2 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. As always, strictly read and follow the directions provided on the product label before using any pesticide. For more information about the impact of fire ants on Texas agriculture, and more about the 2-Step Method, visit https://fireant.tamu.edu/.
