Workers are 1/16 inch long and monomorphic, black in color, with 2 segments in the pedicel. Antennae have 12 segments and a 3-segmented club, and the thorax is unevenly rounded. The black color separates these ants from pharaoh ants, which tend to be light in color.

Little black ants can form large colonies, and colonies have many queens. Their diet varies greatly from sweets to protein and grease.

Little black ants will nest indoors in voids or rotted wood and forage in food-handling areas.