As sure as Spring is here, Summer will not be far behind and with that will come the flies. Horn flies that decrease production and face flies that carry the bacteria that causes Pinkeye. Horn flies cause cattle to have decreased weight gains and overall production in the herd is decreased. The horn flies cause these losses by biting through the skin of the cattle and sucking fluids.
Face flies irritate the cattles' eyes by using rasp-like mouth parts to stimulate tear production.
The face flies feed off of these excess tears. More importantly, the face flies spread the causative Pinkeye agent, Moraxella bovis . Next month's column will discuss Pinkeye prevention and treatment in detail. Both face flies and horn flies develop resistance to insecticides over time. For maximum prevention, it is advisable to switch the class of drug you use each year or two.