How do imported fire ants enter homes and other structures? Imported fire ants can enter homes to forage or nest. Once inside, they can affect people (Drees 1995) and pets and forage on available food. Colonies (including worker ants, brood, queens and winged sexual male and female reproductive ants) can migrate into homes and other structures in search of food, water and nesting sites. They are sometimes aggravated to do so during periods of extreme outdoor heat/drought or flooding rains and enter through any cracks and crevices that allow them to gain entry.
How to get rid of them:
One method of preventing fire ant problems in structures is to prevent their entry by eliminating, or restricting, points of entry. Several weep hole covers have been marketed for use to exclude ants from entering structures, and some of these have been shown to effectively exclude the red imported fire ant, S. invicta (Drees, 2002). An aperture of 0.5 mm should exclude red imported fire ants. However, achieving exclusion using spackling, caulk or other sealants can be difficult or impractical.
Another method is to treat fire ant nests with an insecticide or fire ant bait. If the ants are nesting outside and coming into the house for food the best way to control them is to treat the nest outside directly with a pesticide. The situation is more complicated if the ants are nesting inside the house. There are baits formulated for indoor use that can be used, which the workers will take back to the colony and feed to the queen. Trails of foraging ants can be sprayed with a contact insecticide, but these treatments do not directly affect the colony. If the ants are nesting in a wall, an outside perimeter treatment may actually make things worse by acting as a repellent and keeping ants indoors. For ants nesting in walls, a contact insecticide should be used and it may require assistance from a professional pest control operator. Make sure the product you select is labeled for use indoors. Read and follow the directions on the product label for best results. Be sure to keep products away from small children and pets. For more information see:
Tips for managing imported fire ants in homes and structures are available at Management Options of Fire Ants for Homes and Buildings.
Citations
Drees, B. M. 1995. Red imported fire ant multiple stinging incidents to humans indoors in Texas. Southwestern Entomol. 20(3):383-385.
Drees, B. M. 2002. Evaluation of Guest Control, Inc. weep-hole screens for brick veneer structures in Red Imported Fire Ant Management Applied Research and Demonstration Reports 200-2002, Texas Imported Fire Ant Research & Management Project. Texas A&M University System. College Station. P. 17. at http://fireant.tamu.edu/research/arr/year/00-02/2000-2002ResDemHbk.htm#weephole.
