Horses and ponies find flies highly irritating, both mentally and physically. They often affect a horse's ability to focus or concentrate and can cause severe irritation and distress.
In some cases, irritation from flies can lead to sores developing that might prevent your horse being ridden and can also lead to skin infections. A variety of diseases can be passed onto horses by biting insects, fortunately few are an immediate threat to UK horses, however, climate change and the increase in global transport may change this in future years.
Do you know your flies?
Peak months: Mid-summer to autumn
Location often found on horses: Eyes or lower limbs
Stable flies are surface feeding biting flies and can be carriers of the stomach worm and the eye worm, whose larvae can cause lesions in the eye's conjunctiva. These flies are active during the day, breeding in organic material, with peak populations in late summer. Stable flies can give a painful bite.
Peak months: Late July to August
Location often found on horses: Body
They give a painful bite by cutting the skin instead of biting taking in the horse's blood. Horse fly bites, therefore, are usually larger and can cause greater skin reactions.
Peak months: Summer
Location often found on horses: Between the hind legs
Crab flies are blood-sucking wingless flies that remain on the horse.
Peak months: Spring to autumn
Location often found on horses: Tail base, head, mane, belly
A midge's bite injects saliva into the skin that can cause an allergic skin condition known as sweet itch.
Peak months: Spring to autumn
Location often found on horses: Inside ears, belly, sheath
Black flies cause crusting from the location they suck from; they also are thought to be involved in the development of aural plaques and possibly equine sarcoids.
The House or Face fly
Peak months: Late summer
Location often found on horses: Face and nostrils
These flies breed in dung and decaying organic matter, ensuring general hygiene around the stable and field is important.
Fly reduction strategies:
Fly repellents - containing DEET (Diethyl-m-toluamide) or Permt hrin are thought to be more effective at repelling insects than those without this ingredient and are offered in spray and gel. We recommend testing a small patch of your horse's skin for any adverse reactions before using any insect repellent all over the body.
Fly rugs - provide a physical barrier between the horse and the flies, reducing what skin is exposed to potential bites. Fly rugs are designed to be breathable and suitable to wear in all weathers, making them an easy to use and practical way of managing fly irritations. All horses and ponies wearing fly rugs should be checked daily for rubbing or irritation from their rugs. (If your horse suffers from sweet itch, it is important to check the rug is also effective in preventing midge bites as not all fly rugs prevent access by the smaller midge).
Stables and paddocks - if possible, horses and ponies should be turned out in fields away from ponds, streams and wooded areas. Choosing a field with open winds will also help reduce bites as flies find it harder to land in strong winds. The muck heap should also be as far away from the paddock and stables as possible. Midge activity is highest at dawn and dusk so stabling horses susceptible to sweet itch at these times during the summer is best. Fly screens can also be fitted to stable doors, using insect repellent strips, as well as the use of a fan in the stable will also help as this creates air movement. Midges cannot fly against a wind stronger than 5mph.
Contact Milbourn Equine, vets in Rye, East Sussex if you would like further information, help or advice on flies this summer.