Fire ants: identification & fire ant control

Signs of fire ants in your home

• Fluffy dome-shaped mounds with no visible entry hole
• Ants boiling out when the mound is disturbed
• Burning stings that form white pustules

Is it really fire ants? Side-by-side comparisons

Harvester ants are larger, often reddish-orange, and their mounds typically have a cleared, circular area devoid of vegetation; fire ant mounds are irregular and dome-shaped.

Native fire ants are typically smaller and build less conspicuous mounds; imported fire ants (*S. invicta*) exhibit polymorphism with workers of various sizes within the same colony.

Pavement ants are dark brown to black, smaller, and build nests under rocks or pavement with excavated soil forming small craters; fire ants are reddish-brown and construct prominent soil mounds.

Big-headed ants have distinct major workers with disproportionately large heads, a feature absent in polymorphic fire ant workers; fire ants also possess a painful sting.

Regional differences across the U.S.

The imported fire ant species, primarily *Solenopsis invicta*, dominates the southeastern United States, extending from Florida to eastern Texas and northward into parts of Arkansas and North Carolina. Its northern expansion is limited by cold winters, but milder winters due to climate change could allow further spread. *Solenopsis richteri*, the black imported fire ant, is established in parts of northern Mississippi and Alabama, sometimes hybridizing with *S. invicta*. In warmer, more humid regions like the Gulf Coast, colonies can be more numerous and larger due to extended foraging seasons and optimal soil moisture for mound construction. Conversely, in drier regions of Oklahoma and Texas, fire ants might aggregate near irrigated lawns or water sources. Seasonal activity peaks in spring and fall, with reduced foraging during extreme summer heat or winter cold.

Life cycle and timing that changes treatment

Fire ant colonies contain a queen, workers, and brood (eggs, larvae, pupae). Eggs hatch in 6-10 days, developing into adults in 20-45 days, depending on temperature and food availability. Multiple generations occur annually, with queens continuously laying eggs. Mature colonies can produce winged reproductive alates that swarm, typically after rain during warm seasons, to establish new colonies. Colonies overwinter as active adults within the mound, surviving freezing temperatures by tunneling deeper into the soil.

How to inspect for fire ants, step by step

1. 1

   Carefully observe areas of direct sunlight, such as lawns, pastures, and highway margins, for dome-shaped soil mounds, particularly after rainfall. Use a stick to gently prod a suspected mound; fire ants will rapidly emerge.

2. 2

   Inspect utility boxes, electrical equipment, and irrigation control boxes. Fire ants are drawn to electrical currents and can nest inside, causing damage and creating a sting hazard. Use a flashlight for internal inspection.

3. 3

   Check along sidewalk and driveway edges, as well as under landscaping timbers or stones, for signs of cryptic mound formation or foraging trails. Fire ants often construct tunnels along these structures.

4. 4

   In cooler weather or during the hottest parts of summer, inspect areas of partially shaded ground adjacent to sunny spots, as fire ants may shift foraging or nesting locations to moderate temperature extremes.

Treatment decision tree

Fire ants questions homeowners ask