According to Orkin, a number of different species may inhabit a bathroom, and most do so because of the moisture that is available. The carpenter ant, a large, black ant that lives in wood and is drawn to moisture, is one example. Odorous house ants are another possibility.
The odorous house ant grows approximately 1/16 to 1/8 of an inch in size. It is characterized by a dark-colored body and an unevenly shaped thorax. These ants are common indoor pests and eat honeydew along with other sugary foods. This species is extremely hardy and resistant to temperatures that would make other ants uncomfortable. Injured members of the colony, including the queen, can function normally if incapacitated.