The odorous house ant is found throughout North America and is a common house-infesting pest in Virginia. This pest is often found foraging for food in long trails over household surfaces and can contaminate food products. Although these ants do not bite or sting, they are a persistent nuisance pest once they begin foraging indoors in large numbers.

Odorous house ants are tiny, about 3 mm in length, and are dark brown to black in color. They can be taxonomically identified by having a single node on the petiole that is hidden from above by the abdomen. However, odorous house ants are most easily identified by the coconut odor that is produced when their bodies are crushed. It is from this odor that they get their name, odorous house ants.

These ants are almost always seen foraging in large numbers. When alarmed, the workers will run about in an erratic fashion with their abdomens raised in the air.

Like all ants, odorous house ants live in social colonies. These colonies are made up of different cast members (workers and reproductives). Male and female reproductives are often called winged swarmers.* Swarmers first appear in the early summer months. Male swarmers will emerge from the parent colony first, followed by the new queens. A few days after mating, males usually die and the mated females begin new colonies. When a new colony is initiated, a queen lays a small batch of eggs and tends the larvae that hatch. The adults that develop become workers and take over colony labor activities. Once a colony has been established, queens will continue egg laying until late fall. During the winter months adults are inactive and the larvae slow their development. In the spring, workers begin to forage and queens resume their egg laying. Larval development and production increases so the colony can grow substantially during spring and summer. Colonies can be very large, ranging in size from several hundred to over 100,000 individuals. In addition, odorous house ant colonies can produce hundreds of laying queens and thousands of workers.

Non-Chemical. The best way to control odorous house ants is prevention. Good sanitation is a vital part of an effective ant prevention program. You should remove potential food sources inside the home by wiping up spills and counter tops and by storing foods in sealed containers. These measures will help remove potential food sources that are attractive to odorous house ants. If ants are seen coming into the building from the outside, then they can be discouraged by sealing up holes, cracks and crevices in the structure. Odorous house ants can also be discouraged from entering the home by removing potential harborages that may serve as nesting sites such as: debris, stacks of firewood or lumber. Trimming back vegetation and landscaping so that they do not contact the building will also eliminate possible routes of entry into the structure from the outside.

Even with preventative measures, control of odorous house ants is difficult. Control can be accomplished if the ant nest(s) is located. Sometimes the nest can be found by making careful observations and following the foraging trails back to the nest site. Once the nest is found it should then be removed. However, nest location is difficult and often impossible. Therefore, there are several alternative approaches using insecticides that can be taken to control an infestation.