At night flies may leave the animal and rest in barns or on plants. When on the animal they rest on the back, sides, and belly, usually with their heads pointed downwards. Some animals can harbor thousands of flies at one time. Annoyance to cattle caused reduced food consumption, thereby reducing weight gain and milk production. Larvae can be found in cattle manure.
Flies build up in high numbers on cattle.
For additional information, contact your local Texas extension service agent, or search for other state extension service offices.