Red imported fire ants produce hills or mounds in open areas where the colonies reside, although colonies occasionally occur indoors and in structures such as utility housings and tree trunks. Disturbance of mounds results in a rapid defensive response by worker ants, which quickly run up vertical surfaces. Worker ants range from 1/16 to 3/16 inch (1.5 to 5 mm) in length and are dark brown. Queen ants are larger (3/8 inch) and have no wings after mating. There are three other species of fire ants that are native in Texas (the tropical fire ant, Solenopsis geminata Fabricius; the southern fire ant, S. xyloni McCook; and the desert fire ant, S. aurea Wheeler) and a number of other native ants.
Life Cycle: Eggs hatch in 8 to 10 days, and larvae develop through four instars before pupating. Development requires 22 to 37 days, depending on temperature. Fire ants are social insects, and each colony contains one or more queen ants. Queen ants can produce about 200 eggs per day. A "mature" colony can contain over 200,000 ants along with the developmental and adult stages of winged black-colored male and reddish-brown female ants called "reproductives." These ants stay in the colony until conditions exist for their nuptial flight.
Habitat, Food Source(s), Damage: Mouthparts are for chewing and sipping. Only the last larval stage can injest solid food particles. Sieve plates in the mouths of worker ants prevent ingestion of food particles. Fire ants infest the eastern two-thirds of Texas. Fire ants are omnivorous, but their primary diet consists of insects and other invertebrates. Predatory activities of fire ants suppress populations of ticks, chiggers, caterpillars and other insects. Predatory activity attributes to wildlife reductions in some areas.
Pest Status: Sterile female fire ant workers can sting repeatedly. They first bite, and while holding on to the skin with their jaws, inject venom with stingers at the end of their abdomens. The unique venom produces a fire-like burning sensation, and most people react by developing a whitish pustule or fluid-filled blister at the site of the sting after a day or two.
References and Resources: For additional information, contact your local Texas Cooperative Extension agent or search for other state extension office; Brandenburg and Villani 1995; Drees et al. 1996; http://insects.tamu.edu.