Odorous House Ant

Tapinoma sessile

The odorous house ant is native to most of the entire United States ranging from Canada into Mexico. These ants feed on many different items including most items found in homes but apparently prefer to feed on those high in sugars. Outside, Tapinoma sessile will feed on honeydew excreted by aphids and on nectar from flowers and buds.

Description and Behavior

Workers are 1/16 to 1/8 inch (2.4-3.3 mm) long and monomorphic (all members are about the same size). The body is uniform in color from brown to black, antenna is 12-segmented without a club, thorax is uneven, and pedicel has one hidden node. There is no circle of hairs at the anal pore. A distinctive characteristic of this species is the rotten odor when crushed.

Odorous House Ant, Tapinoma sessile (Marion R. Smith, USDA)

Life History

Odorous house ants can develop extremely large colonies but tend to maintain colonies of only several thousand workers with many queens. Winged reproductives appear in May through July. Workers are very active and move rapidly in single files. They mostly prefer sweets but will also feed on dead insects and grease. Nests are typically found outside under rocks, boards and the like, but can also nest within structures. Colonies are from hundreds to many thousands of individuals in size.

Odorous house ants will nest indoors near sources of moisture and warmth, in voids, but also in termite-damaged wood. Their ability to feed on many types of food brings them into conflict with us when they contaminate stored products in the pantry.

Management

Control of foraging odorous house ant workers can be accomplished through the use of baits. The workers carry the baited material back to the nest, eliminating the colony. Many different types of bait are available to the homeowner in this regard. However, baits containing hydramethylnon, fipronil or boric acid are slower acting and do not kill the workers before they have had a chance to share the baits with the queen and developing immature ants. Choose baits designated for sweet-loving ants. Place the baits in areas where ant activity has been observed and make certain that children or pets cannot reach them. Maintain sufficient amount of baits to satisfy the colony by replacing used baits. It may require two weeks or longer to obtain control.

Warning

Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.

Authored by: Steve Jacobs, Sr. Extension Associate

January 2014