—Amanda Gee, Purdue University
One of the best ways to keep cattle healthy and gaining pounds in hot weather is to control flies, a Purdue Extension beef specialist says.
Heavy populations of flies can cause stress in cattle herds and spread disease. Both stress and disease can reduce milk production and calf gain.
"We're into June, so producers should start looking for the fly populations, and they need to knock those fly populations down soon," Ron Lemenager said.
There are two main fly species that Indiana cattle producers need to worry about: the horn fly and the face fly.
The horn fly is a small, blood-sucking insect that feeds mainly on the backs, sides, shoulders and underlines of cattle. They reduce weight gain and make animals more prone to stay in the shade instead of going out in the sun to graze, Lemenager said.
Horn flies are usually easier to control than face flies because they don't travel far.
"Horn flies typically stay with the animal, only leaving to deposit eggs in manure," Lemenager said.
Face flies are known to travel more from animal to animal and from farm to farm.
"If neighbors aren't controlling face fly populations, you will get more flies bothering your herd," Lemenager said.
Non-biting face flies are about twice the size of horn flies and similar in size to houseflies.
Face flies feed on the secretions around the eyes and heads of cattle. In addition to irritating the skin, they can spread pink eye, Lemenager said.