Summer Pest Management

Summer is definitely upon us as are the pests of summer.  Having had such a mild winter there seems to be an overabundance of these irritating pests this year.  Horse flies, deer flies, face flies and horn flies are what our horses are bothered by primarily in the pasture, particularly in areas that are near woods or wet, marshy areas.

Female horse flies and deer flies are blood-sucking feeders that are not only extremely annoying but can cause fatigue, pain, blood loss, and weight loss in extreme numbers.  They land, cut through the skin of the horse with scissor-like jaws and feed on the blood that pools around the wound.  Even after they fly away, the wound continues to bleed and then can attract face flies.  Horse and deer flies are very difficult to control because they only land on our horses long enough to feed it it difficult to deliver a dose of insecticide lethal to them so we have to rely on repellants.

Face flies and horn flies resemble house flies.  Adult female face flies cluster around the eyes, nose, and muzzle.  Clusters around the eyes can cause eye issues such as pinkeye and eyeworms.  They also gather around wounds left by biting flies to continue to feed causing further blood loss. Horn flies have piercing mouths to penetrate skin to suck blood.  They are intermittent feeders that take 20+ small blood feedings a day.  They typically gather on the shoulders, backs and sides but are found on the bellies in rainy or very hot weather.

Because of health issues these flies can cause in our horses, pest management is important.  Some recommendations are:

• Manure management – regular dragging of pastures to spread fresh manure or complete removal of piles can be effective as some species of flies breed on fresh manure.
• Avoid (when possible) standing, stagnant water
• Keep your horses clean – muddy, matted hair attracts even more flies
• Fly masks are effective barriers from face flies – just be sure to remove them regularly to check your horses’ eyes.  Fly sheets are also an option but choose one that is light-weight, light-colored and/or light reflective for the very hot days. (And be certain it fits well!)
• Pesticides, when used, should be applied daily as the active ingredients break down quickly and do not provide effective long-term control.  The most effective repellants contain pyrethrins or pyrethroids so check the labels. Sprays and wipes are most commonly used.

While pest control can be difficult and options are limited we should use what we can to make our horses as comfortable as possible during the upcoming summer months.  They’ll appreciate it and in turn so will you!

Sources:

Phil Daufman and Don Rutz, Department of Entomology, Cornell University

Charlie Pitts, Department of Entomology, Penn State

Lee Townsend, Extension Entomologist, University of Kentucky