Workers are 1/16 inch long and monomorphic, tan to brown in color but usually lighter than other tiny ants and have very tiny compound eyes and 10-segmented antennae with a 2-segmented club. The pedicel has 2 nodes, and the thorax has an uneven profile. Stinger is very small. This ant and the pharaoh ant are often misidentified because of their similar size and color.

Colonies may have up to several thousand workers and multiple queens. They tend to nest in or close to the nests of other ants and will steal food and larvae (as food). There is a strong preference for protein, as thief ants will feed on animal carcasses, but they are also attracted to sweets.

Thief ants will enter structures through cracks in the foundation or small openings in woodwork and commonly during hot weather. They forage in trails throughout a structure seeking protein, sweets, and liquid. Outdoors, they nest under objects and in soil.