[August Pest ID] Fire Ant

Scientific Name: Solenopsis spp.
Order/Family: Hymenoptera/Formicidae   

Description
Fire ant workers vary in size, ranging from 1/16- to 1/4-inch long and are yellow to dark red-brown. The thorax lacks spines, and the petiole has two nodes. They have a stinger at the tip of the abdomen and ten-segmented antennae, which is tip­ped with a two-segmented club.

Biology

The red imported fire ant single-queen colonies range in size from 80,000-250,000 workers and 30-100 mounds per acre. Multi-queen colonies have fewer workers per colony but 200-700 mounds per acre. Queens can produce approximately 1,500 eggs per day. The larvae mature into workers in 22-38 days. Minor workers live 30-60 days, intermediate workers 60-90 days, and major workers 90-180 days. Queens live from two to six years. Males die shortly after swarming. Six to eight swarms occur each year.

Habits
Several species of Solenopsis are called fire ants because of the fiery pain their stings inflict upon the vic­tim. These ants usually nest in the ground but can develop col­onies in structures, especially in areas near the soil. They are attracted to electrical junction boxes, such as air conditioners and traffic signals. When nesting in the soil, they build large, unsightly mounds which are a detriment to cultivation of fields. Some species of fire ants nest in typical ant habitats, such as under stones, landscape timbers, in voids and around foundations.

Control

Fire ants can cause problems in structures if the workers are habitually foraging in the structure for food. These areas can be partially protected from ants originating in outdoor mounds by applying barrier sprays or dusts of residual insecticides to the soil and foundations around a building. However, this type of treatment is not as effective as treatment of the nest itself. Nests often require several treatments, especially if they are large and well established. Direct mound injection and drenches can be used successfully to reduce, and in some cases, eliminate the colony. Baits that contain an insect growth regulator (IGR) and/or a slow-acting stomach poison also are successful in eliminating colonies. The so-called “two-step method” is widely used featuring broadcast application of a bait product and individual mound treatments with a dust, granule, bait or drench insecticide. Interior areas should be thoroughly treated with residual insecticides, especially in areas where ants appear to be entering­­ or traveling.