Flies can be a nuisance for cattle breeding operations by biting and irritating the animals and their caretakers . Irritated cattle feed less and develop more slowly. Poor manure management can lead to large numbers of flies that breed in the manure. One solution to the fly problem is to put pesticides in the cow diet that will kill or control the fly larvae without harming the cow. A downside of this method is the killing of non-target insects that are competitors, predators and parasitoids of the flies. Elimination of predators and parasitoids can create additional fly problems. Elimination of competitors and the flies themselves can interfere with the decomposition of manure. Cow manure can cover foliage, prevent plant growth and foul pasture. Fly larva insecticides have their place, but are not a substitute for comprehensive manure management.
Ralf Jochmann, Wolf U. Blanckenhorn. Non-target effects of ivermectin on trophic groups of the cow dung insect community replicated across an agricultural landscape. Basic and Applied Ecology
Volume 17, Issue 4, June 2016, Pages 291–299.