sentences:  Barn swallows (and other small passerines) often have characteristic feather holes on their wing and tail feathers.These holes were suggested as being caused by avian lice such as "Machaerilaemus malleus" and "Myrsidea rustica", although other studies suggest that they are mainly caused by species of "Brueelia".Several other species of lice have been described from barn swallow hosts, including "Brueelia domestica" and "Philopterus microsomaticus".