Odorous House Ant: Tapinoma Sessile

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.

*Ant swarmers are sometimes misidentified as termite swarmers. Ants can be identified by having the front wings larger than the hind wings. Wings on termites, however, are considerably longer than the body and both wings are the same size.

Odorous house ants are very opportunistic and can nest in many different places both indoors and out. Outdoors, odorous house ant nests are usually shallow and may be found just underneath the soil surface. These nests may be found in mulch, soil, debris, logs, stumps, under stones and under plastic outdoor tarps. Indoors, nests are usually found in wall voids, around hot-water pipes and heaters, behind paneling, under carpets or beneath the floor. Sometimes these colonies can become so large that they eventually bud. Budding is a process by which the parent colony splits to form satellite colonies. The satellite colonies remain inner-connected to the parent colony by foraging trails. These trails provide for the exchange of workers, food, and larvae.

odorous-house-ant-foragingOdorous house ants forage both night and day and eat many types of foods. They eat live and dead insects but are also very attracted to sweet foods. They especially like the honeydew that is produced by aphids and mealybugs. Many colonies of odorous house ants tend or herd aphids and mealybugs to collect the honeydew they excrete.

Source: L. Barbani, Extension Specialist, Entomology; R. Fell, Extension Specialist, Entomology; and D. Miller, Extension Specialist, Entomology; Virginia Tech

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