Indoor Fire Ant Invasions

Fire ants entering a building around an infrequently used door.

Fire ants are outdoor, soil-dwelling insects. They rarely invade buildings, but when they do, they usually cause problems.

Indoor fire ant invasions happen for two reasons. The first is when foraging workers wander into a building, find a food source, such as pet food or spilled food crumbs, and recruit other workers to this food source. This results in a trail of workers traveling back and forth from the outside nest to the inside food source and a concentration of ants around the food source.

The second cause of indoor fire ant invasions is when an entire colony of fire ants attempts to relocate because of disturbance by flooding, drought, landscaping or other causes. This is less common, but more distressing. In this case, you usually see large numbers of workers carrying their white brood into the house. They may also bring particles of soil inside. These displaced colonies are usually very agitated and will sting aggressively and in large numbers. They have to be controlled quickly and effectively. See Extension Publication 2443, Control Household Insect Pests, Pages 15-16, for more details on how to control and prevent indoor fire ant invasions.

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