This is a family of about 150 species in North America. Almost all species are very small adult beetles that are usually associated with fungus of some kind. They may also occur in old bird or rodent nests as well as occasionally infesting foods that are in poor condition. Their presence in a structure may be an indication that an excessive moisture condition is present with growth of molds or decay fungi. They may also be in grain-based foods that have been stored too long or in damp condition, and around 2 dozen species have been identified as pests of stored foods.
Since they are associated with conditions or foods that are not wanted in a structure the source of the infestation needs to be discovered and corrected. Insecticide applications may not be necessary and will be of little help until the source is found.