Red imported fire ants infest the eastern two-thirds of Texas and continue to spread westward. They arrived in the state during the 1950s after entering the U.S. through the port of Mobile, Alabama, around the 1930s. Today they occupy more than 260 million acres across nine southeastern states, but Texas bears some of the heaviest consequences, with agricultural damages alone exceeding $90 million per year.
How They Spread Across the State
Fire ants reached Texas through a combination of natural dispersal and human activity. Mating flights carry new queens several miles through the air, where they land, shed their wings, and start new colonies. Entire colonies can also relocate by mass movement on the ground or by floating on floodwater. That last strategy is more than a curiosity: fire ants interlink their legs to form a raft-like structure that keeps the colony afloat as a single unit until they reach dry land. During Texas flood events, these living rafts drift until they contact a person, tree, or fence post, then rapidly climb upward and disperse.
Human commerce accelerated the spread dramatically. Nursery stock, sod, hay bales, and soil shipments carried colonies into new counties faster than mating flights ever could. The result is a population that now blankets everything from the Gulf Coast to the I-35 corridor and continues pushing into drier western regions where irrigation and urban landscaping provide enough moisture to sustain colonies.
Single-Queen vs. Multi-Queen Colonies
Texas has two distinct colony types, and the difference matters for anyone trying to manage them. Single-queen (monogyne) colonies have one reproductive female per mound. Workers are territorial, defending their turf against neighboring colonies, which naturally limits how dense the mounds get. You’ll typically see fewer than 300 mounds per acre in monogyne areas, with each mound relatively large.
Multi-queen (polygyne) colonies are a different problem entirely. A single colony can house hundreds of unrelated queens. Workers move freely between mounds and share resources, so there’s no territorial spacing. Mound densities exceed 300 per acre, sometimes dramatically. The individual mounds tend to be smaller and flatter, making them harder to spot, but the total number of ants per acre is far higher. Polygyne infestations are especially common in urban and suburban areas of central and east Texas.
What a Fire Ant Sting Does to Your Body
A fire ant grips your skin with its jaws, then pivots and stings repeatedly in a circular pattern. The venom contains two main components: an oily alkaloid that kills cells on contact, and a small protein fraction that triggers immune responses in sensitive individuals. The alkaloid is responsible for the burning pain and the signature white pustule that forms within 24 hours. Dead cells at the sting site attract white blood cells, which accumulate and create that fluid-filled bump.
For most people, fire ant stings are painful but not dangerous. The pustules itch intensely for several days and carry a risk of secondary infection if scratched open. For a small percentage of the population, though, the protein component of the venom triggers a severe allergic reaction. In states where fire ants are established, the prevalence of fire ant venom anaphylaxis is roughly 8.5 per 10,000 people. That’s a small number overall, but given how common fire ant encounters are in Texas, it adds up to a meaningful number of emergency situations each year.
Signs of a systemic reaction include rapid flushing, hives spreading beyond the sting site, swelling of the face or throat, chest pain, difficulty breathing, and faintness. These symptoms require immediate emergency care. If you’ve had a systemic reaction before, carrying an epinephrine auto-injector during outdoor activity in fire ant territory is standard practice.
Treating Stings at Home
If fire ants are still on you, pick them off individually rather than brushing or spraying water, both of which can make them grip harder with their jaws and sting more aggressively. Wash the area with soap and water, then apply a cold compress to reduce swelling. Leave the pustules intact. They’re sterile initially, and breaking them open increases the chance of bacterial infection. If a sting site becomes red, warm, and increasingly swollen days later, that suggests infection and may need antibiotics.
Economic Damage Beyond the Sting
Fire ants cost Texas agriculture over $90 million annually. A survey of more than 3,600 Texas agricultural producers found that 37% of total damages came from lost crop yield. The rest split among livestock losses, equipment repair and replacement, veterinary costs, medical expenses, and direct control spending. The geographic variation is stark: farms in southeastern Texas reported average losses as high as $9,438 per operation, while farms in West Texas, where fire ants are less established, averaged just $26.
Electrical equipment is a particular vulnerability. Fire ants are attracted to electrical currents and frequently colonize transformer boxes, air conditioning units, well pumps, and traffic signal housings. They pack the interior with soil and nest material, causing short circuits and equipment failure. In rural areas, damage to irrigation pumps and electrical panels on wells compounds the agricultural losses from crop and livestock impacts.
The Two-Step Control Method
Texas A&M AgriLife Extension developed the “Texas Two-Step” as the most cost-effective approach for managing fire ants on residential and agricultural land. It won’t eradicate them permanently, since reinfestation from surrounding areas is inevitable, but it keeps populations manageable.
Step one is a broadcast application of fire ant bait across your entire yard or property. Baits consist of an insecticide or growth regulator carried on a food attractant, usually soybean oil on a corn grit. Worker ants carry the bait back to the colony and feed it to the queen, which either kills her or stops her from producing viable eggs. Spring and fall are the best windows for baiting, when temperatures are moderate and ants are actively foraging. Bait works slowly, taking weeks to collapse a colony, but it reaches colonies you can’t see.
Step two targets the mounds that are most visible or most problematic, especially in high-traffic areas like yards, playgrounds, and garden beds. Individual mound treatments include liquid drenches and granular contact insecticides applied directly to the mound. These kill the colony within one to two days. Mounds are easiest to locate after a rain, when ants push up fresh soil to rebuild.
The sequence matters. Broadcasting bait first reduces the overall population, so you have fewer mounds to treat individually. Skipping straight to mound treatments means you’re playing an expensive game of whack-a-mole as new colonies fill the gaps left by the ones you killed.
Why They’re So Hard to Eliminate
Fire ants have no effective natural predators in North America. Their colonies are resilient, capable of relocating overnight if disturbed, and queens can live for years while producing thousands of eggs per day. Polygyne colonies are especially difficult because killing one mound barely dents a network of interconnected colonies sharing workers and queens. Flooding, which would destroy most ground-nesting insects, simply triggers raft formation, allowing entire colonies to survive and colonize new territory once waters recede.
Biological control efforts have introduced phorid flies, tiny parasitoids that attack foraging fire ants, at sites across Texas. These flies don’t eliminate fire ant populations, but they reduce foraging activity and give native ant species a better chance to compete. The long-term hope is that a combination of biological controls and sustained management will keep fire ant densities lower than they’d be otherwise, even if eradication remains out of reach.