Specimens from the semiarid areas of northwestern Argentina tend to be smaller and, in many cases although not invariably, darker than most individuals of this species (Lent & Wygodzinsky 1979).

This species is frequently found naturally infected with Trypanosoma cruzi; it colonizes human habitations, and is an important vector of Chagas' disease in certain areas. It also lives in peridomestics areas, such as chicken and pigeon houses, in sparrows nests, and it is also known to occur in rats' nests. It has also been collected in the wild, in bird nests (Lent & Wygodzinsky 1979).