Heat and high humidity levels that returned to the Midwest brought nuisance flies to beef cattle. Producers who have begun fall calving season should give special attention to newborn calves. Biting flies are the most dangerous to newborn calves. Particularly, stable flies and horn flies are of greatest concern due to their ability to overwhelm newborns.
If conditions are favorable for high fly populations, newborns are at great risk. Fly predation on newborn calves can render them nearly incapacitated and result in death. Flies can be attracted by the embryonic fluid and then attack newborns. Flies will concentrate at the part in the hair along the topline and continue until the hide is destroyed and flesh is exposed. Flies will also attack the navel area and continue feeding until the area this area is also irritated and flesh exposed.
The best combat against these serious fly strikes is an aggressive, good mothering cow. According to Michigan State University Extension, cows that aggressively and completely lick calves clean and dry from embryonic fluid will have fewer calves overtaken by fly strikes. Producers should be aware of the potentially devastating feasting that flies can impose and have several products on hand. Fly spray should be applied to newborn calves if flies are present on the animal at a high and nuisance levels. Screw worm sprays can be used on open wounds to protect from maggot development. Wound salves or creams are useful if infestation has been so great as to expose flesh. Wound dressing can aid to heal exposed flesh and protect against further fly strikes. Navels should be dipped with strong tincture iodine to protect from navel infection and deter fly strikes. Close observation of calves that have been severely attacked by flies is critical.
Castration and dehorning of calves should be delayed until after the threat of flies is diminished. Flies can attack and lay eggs into flesh of both knife cut and banded calves. Fly control on mature cows is important. Controlling fly problems on the entire herd will greatly minimize problems associated with fly strikes on newborn calves.