The little (or sometimes lesser) house fly is a common pest of poultry, particularly at caged layer facilities where immature flies develop in the manure accumulating beneath confined birds. In the arid southwestern United States, this fly species is most abundant during the cooler spring and fall months. Male little house flies aggregate into mating swarms within poultry houses as well as beneath shade trees, in building doorways, and in other areas protected from wind and direct sunlight that are near to development sites. This male swarming behavior combined with their dispersal into neighboring residential areas can result in nuisance to nearby homeowners.