Odorous house ant workers are brown to black and 1/16-to 1/8-inch
long. The thorax has no spines, and the petiole has one segment
which, when viewed from above, is hidden by the rest of the abdomen.
There is a slit at the tip of the abdomen instead of a circlet
of hairs. The best identifying characteristic is the "rancid
butter" smell these ants produce when they are crushed; hence
their name. When alarmed, the workers scurry around with their
abdomens raised in the air.
Odorous house ants often nest outdoors under stones, logs, and
in the nests of larger ants. They con also nest indoors in wall
or floor voids, around heat sources, (e.g., hot water pipes
and heaters, crevices around sinks and cabinets). Odorous house
ants travel in trails and prefer sweets, although they eat almost
any household food. They usually invade structures during rainy
periods after honeydew on plants has washed off.