Do Fire Ants Nest Under a House?
- While people think of fire ants as one type of ants, there are several types of fire ants. Most of the attention goes to the red imported fire ant (Solenopsis invicta) which is not native to the U.S. but has become common in the southern United States. It is the most aggressive variety of fire ant and most likely to attack. Another non-native species is the black imported fire ant (S. richteri). Fire ants native to the United States include the tropical fire ant (S. geminata) and the southern fire ant (S. xyloni).
- Unlike most other ant species, fire ants prefer to build their nests in a sunny location in open, grassy areas. They look for loose soil that is well irrigated. Nests may be near a house, but not under a house. However, fire ants will nest in dark protected sites if there is enough moisture and food, according to Timothy C. Lockley of the Imported Fire Ant Station. They have been found nesting in rotten logs, walls of buildings, automobiles, electrical equipment and utilities. They will also build nests under roads, sidewalks, pavement and buildings.
- Fire ant nests are often associated with large mounds in the soil, but the ants may not build a nest if they are nesting under your house since nests are not essential for a colony's survival. Mounds average about 15 to 18 inches wide and 8 to 12 inches high, but size will vary depending on the type of soil. The mounds indicate where the nest is located, but not the opening. The mounds are used to raise the colony above the water table, which is why they may pop up after it rains. The mound also helps keep the colony warm in the winter by collecting sunlight. Mounds are usually less noticeable in the late summer and early fall.
- If fire ants are nesting under your house, you should be able to find one or more nest entrances near your home's foundation. Fire ants usually have multiple entrances to their nests. Unlike the mounds, nest entrances are usually obscure and irregular. They usually are found next to objects or debris and you may see scattered soil around the entrance.