Odorous House Ant

The odorous house ant is one of the most common household ants in North America, nesting both outdoors in soil and mulch and indoors within wall voids, under floors, and near leaky plumbing. Its scientific name, Tapinoma sessile, reflects its low-profile build, and its common name comes from the distinctive smell released when a worker is crushed.

Colonies are flexible in size and structure, ranging from a few dozen ants with one queen to sprawling, multi-queen networks with thousands of workers spread across several interconnected nest sites. This adaptability allows the species to thrive in a wide range of habitats, from forest leaf litter to suburban kitchens.

Odorous house ants are native to North America and are especially active in warm weather, often moving indoors in search of moisture during droughts or heavy rains.

• Small workers, 2.4-3.3 mm, dark brown to black
• Single small node on the petiole, usually hidden from above by the gaster
• Uneven, somewhat humped thoracic profile when viewed from the side
• Releases a strong rotten-coconut odor when crushed, the most reliable identification clue
• No stinger; moves in loose, meandering foraging trails
• Similar in size to little black and pavement ants but distinguished by odor and hidden petiole node

Found throughout much of North America, this species nests in soil under stones, logs, mulch, and leaf litter, as well as in wall voids, insulation, and beneath flooring in buildings. It favors areas with reliable moisture and often relocates nests seasonally, moving colonies indoors during extreme heat, drought, or heavy rainfall.

Odorous house ants are opportunistic omnivores, feeding on other insects, plant nectar, and sugary foods, with a strong preference for honeydew produced by aphids and other sap-feeding insects, which they tend for this resource. Foraging workers travel along semi-permanent trails between nest sites and food sources. Colonies may contain hundreds of queens and readily bud into new satellite nests when disturbed or when populations grow large.

Development follows complete metamorphosis through egg, larva, pupa, and adult stages. Because colonies are polygynous, brood production can continue across multiple nest sites simultaneously. Reproductive swarms of winged males and queens typically occur in late spring or summer, though budding by existing queens is a more common way new colonies form.