Besides inflicting annoying bites on both man and beast, bloodsucking insects transmit diseases including equine infectious anemia (swamp fever) and encephalomyelitis.
Here's a roundup of the ways to lower your insect population around the horse barn and increase the pleasure of summer horse ownership.
Tabanids include deerflies and several types of horseflies. Deer flies are small, yellowish-orange flies with dark body markings; horseflies vary greatly in size, color, and body and wing markings. Both types take blood meals every three to four days.
The bite of a tabanid fly is painful and, because of blood loss, local reactions to the bites may result in nodules on the skin. Because of the painful bites, general annoyance and potential for disease transmission, controlling these flies should have a high priority.
Control: Tabanids prefer wooded areas and thick vegetation; horses in open pasture have fewer problems. These flies rarely enter barns and are most active at twilight.
Using electric light insect traps in the barn may be useful for horseflies, but frequent use of repellents is the most practical control method.
Blackflies, commonly called ear gnats, feed on blood inside the ear. They are found throughout the United States, especially near running water. Female blackflies feed on blood every three to five days.
Extreme annoyance and itching result from the flies feeding inside ears, along the neck and chest, inside the thighs and along the underside of the horse. Repeated bites cause bloody crusts or scabs.
Control: Stabling horses during peak fly feeding times helps. Frequent use of repellents and ear nets also help control the attacks. Applying petroleum jelly inside the ears after clipping may help, too.
Biting midges, commonly referred to as "no-see-ums" or sandflies, are small flies that cause an allergic reaction known as culicoides hypersensitivity or "sweet itch". Midges feed by inflicting painful bites which causes extreme itching, usually along the base of the tail, mane and withers.
Because the horse gets so itchy, he may rub his mane and tail down to bleeding skin. This condition may also involve the horse's chest underside and face. Midges prefer areas of high humidity such as damp pastures or edges of ponds. Like deer flies, they feed at dusk.
Control: Stabling horses at peak midge feeding times and placing a fan outside of the stall will help, as well as placing mosquito netting or screening over stalls.
Horses suffering from hypersensitivity reaction may require treatment by a veterinarian.
Horn flies are small, biting flies associated with cattle, but are frequently found feeding on the abdominal midlines of horses, particularly those pastured near cattle. Both male and female horn flies are blood feeders and take 20 to 30 meals per day. Repeated bites cause crusty, ulcerated lesions.
Control: Separating horses from cattle and applying insect repellents frequently will minimize the bites. Using corticosteroid-antibiotic creams may also help minimize inflammation.
House flies, stable flies and face flies are all responsible for transmitting diseases; however, only stable fly bites cause serious blood loss.
Stable flies attack horses' legs and abdomens, and bites result in nodules and crusty lesions. Both house flies and face flies feed on secretions around the horse's eyes and cause considerable annoyance.
Control: Using repellents and insecticides on legs and abdomen helps minimize stable fly bites. Applying repellents to the back and neck can help control house and face flies. Face masks also help reduce eye irritation.
Mosquitoes are the most prevalent type of blood-sucking insect. Their most active feeding period is the first two hours after sunset, particularly in warm, moist weather. Their vicious bites transmit several viral diseases in horses.
Control: Water management (draining standing water, draining troughs) can reduce mosquito populations. Using barn sprays and applying repellents can reduce mosquito population.