The South American hoary bat, Lasiurus villosissimus (É. Geoffroy Saint-Hilaire, 1806), is a vespertilionid bat, endemic to South America and occurring in all countries except Guyana, French Guiana, and Suriname. It is one of the four species included in the subgenus Aeorestes. Lasiurus villosissimus is distinguishable from all other species of the genus by its larger size and coloration (except Lasiurus cinereus, but it only occurs in Mexico, Central America, and the Hawaiian Islands). Pelage is dark brownish and grayish mixed with yellow, tinged with white, producing a frosty or hoary appearance which is always evident. It is an insectivorous species that inhabits a great variety of habitats.