The Houston area has a lot of ants. Red imported fire ants alone have colonized nearly every yard in the region, and they compete with and displace a lot of the native species that used to be here. But there are still half a dozen other ant types that turn up regularly in Houston and Katy homes, and what works on one species often does nothing to another. Getting the identification right is step one.
Quick answer
Fire ants build dome-shaped mounds with no visible entry hole at the top, sting (not just bite) when disturbed, and their venom causes a burning welt. Regular ant species like odorous house ants or carpenter ants look different and behave differently. The treatment for each is not the same.
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How to Spot a Fire Ant Mound
Red imported fire ants build the classic dome-shaped mounds you see scattered across lawns and roadsides. The mound has no visible hole at the top. Fire ants enter and exit from underground tunnels below. Touch the mound and thousands of workers will boil out in seconds. The sting is sharp and distinct: a burning sensation followed by a white pustule that forms within twenty-four hours.
Fire ant colonies can be massive, with a million workers or more in a well-established mound. In Houston's warm climate they are active year-round, and a single large yard can have dozens of mounds. They are also hazardous around young children, pets, and anyone with a venom allergy.
Common Non-Fire Ant Species in Houston Homes
Odorous house ants are small, dark brown ants that trail along counters and baseboards. Crush one and you get a faint rotten-coconut smell. They are after food and water, and they tend to trail in from the exterior through gaps around plumbing or windows. They bite but do not sting.
Crazy ants (also called Rasberry crazy ants) move in fast, erratic patterns rather than the neat trails you see with other species. They have become a significant pest across the Houston metro and Harris County over the past two decades. Unlike fire ants, they are attracted to electrical equipment and have caused equipment failures. They do not sting.
Carpenter ants are larger, often black or black-and-red, and they do not eat wood. They excavate it to nest in. Finding carpenter ants inside usually means there is moisture-damaged wood somewhere in the structure, because that is what they prefer to hollow out.
Why the Same Treatment Does Not Work on All of Them
Broadcast insecticide sprays tend to scatter ant colonies rather than eliminate them. Fire ants respond well to mound treatments and broadcast bait applied to the lawn, but the bait must be the right type and applied correctly. Fire ants will ignore bait if it is old or applied when the ground is too hot. Texas A&M AgriLife Extension has documented that the two-step method (broadcast bait plus individual mound treatment) is the most reliable approach for fire ant control.
Odorous house ants and carpenter ants are colony-level problems that need gel bait and crack-and-crevice treatment placed exactly where the ants are traveling. Spraying the trail surface drives them away temporarily but does not touch the queen.
Crazy ants present their own challenge because of colony size and because they reject many common ant baits. Effective control usually requires a professional assessment of the infestation's entry points and nesting areas.
What You Can Do Around the Yard and Home
Keeping mulch pulled back from your foundation reduces cover for trailing ants. Sealing gaps around pipes, utility lines, and the base of doors removes the entry points indoor ant species exploit. Fixing moisture issues eliminates the conditions that draw carpenter ants inside. A dripping faucet under a sink or a leaky window seal is all it takes.
For fire ants in the lawn, individual mound treatments buy short-term relief, but a broadcast bait application across the whole yard is what sets back the population at scale. The timing matters. Bait goes down when fire ants are actively foraging, which in Houston means morning or evening when the soil is below ninety degrees.