Common Equine Pest Insects and How to Manage Them
Written by Miquela Allen on July 16, 2019
Many pest insects thrive in the stable environment. Unfortunately, they often cause horses irritation, stress, pain, hair loss and allergic reactions. Some of the most common equine pest insects are common flies, stable flies, horse flies, ticks, gnats, mosquitoes, and bot flies. There are a variety of management techniques that can be effective against these insects.
The common, house, and face flies are all small, non-biting insects that cluster around the tear ducts, nose, and open wounds and feed on discharge from these areas. They breed in manure and decaying vegetation so the most effective management is cleaning stalls and paddocks regularly and keeping the grounds well maintained. Additionally, stable screens and shade can provide relief for horses, as can repellents, which may be applied to the premise or directly to the animals.
The stable fly has a painful bite and can transmit diseases and parasites. This fly feeds on blood and prefers to lay eggs in decaying vegetation including grass clippings, manure, and wet hay and feed, so these flies thrive around horses. The management of the stable fly is similar to that of the common fly, with manure management, shade, and repellants all being effective.
Horse and deer flies also have painful bites and feed on blood. Their saliva causes the horse’s blood to continue to flow, attracting house flies and other pests to the open wounds. These flies lay their eggs in damp soil, so streams, lakes and irrigation ditches are all prime locations. The best approaches to controlling the population of these pests are sprays and repellents.
Ticks are another pest that uses blood as a food source, and around 16 species feed on horses. Aside from the numerous diseases that can be transmitted by ticks, a large number feeding on a single horse can negatively impact the immune system and cause anemia. Overgrown vegetation is the ideal environment for ticks, so mowing, brush removal, and rotating pastures helps keep populations down. Repellents and insecticides can be used additionally to further combat these pests.
Gnats, or biting midges, may be small but are major pests with a painful bite. This bite can cause hypersensitivity known as “sweet-itch” and self-inflicted hair loss, generally along the mane, withers, tail, chest and face. The larvae of these pests can be found in water and decaying vegetation, including manure. Management of these pests includes manure and vegetation maintenance as well as repellents. Fans placed in stalls are also incredibly helpful as the gnats are very poor fliers.
Mosquitoes are a pest most everyone is familiar with. This insect has an itchy bite that can transmit several diseases. Among these are equine infectious anemia (EIA), eastern equine encephalitis (EEE), western equine encephalitis (WEE) and Venezuelan equine encephalitis (VEE). Vaccines are available for EEE, WEE and VEE, and are something to consider in areas with a high mosquito population. These pests breed in standing water, such as swamps and flooded pastures and are able to fly miles from the reproduction site to feed. The best management for mosquitoes is to eliminate standing water, breaking the life cycle. Sprays and repellents that can be effective as well.
The bot flies is a well known equine pest that uses the horse itself to reproduce. Eggs are laid on a horse’s forelegs, shoulders, and lips, and they hatch as the horse rubs and licks the area. The larvae then burrow into the gums and tongue of the horse, where they stay for about a month before migrating to the stomach. Once there they adhere to the mucus membranes passing through the feces eight to ten months later. The mature flies emerge after four to six weeks and the cycle continues. While these flies do not bite, their eggs can cause irritation and larval bots damage the stomach lining, sometimes causing the stomach to rupture. There are medications available that control internal bots and eggs can be removed through scraping, clipping, or the use of a bot knife. Warm water will cause the eggs to hatch prematurely, killing the larvae, so regular bathing can be an effective defense as well.
Overall, keeping the barn clean is crucial, including regularly cleaning stalls regularly and covering feed. Adequate shade and air flow are beneficial as well as most insects prefer bright sun and are weak fliers. Fly masks, like the Crusader, and sheets, like the Rambo Protector with a detachable neck cover, help create a barrier to keep insects off the horses while fly spray and other repellants serve to deter pests from landing and biting. Ultrashield Ex is a sweat resistant fly spray that repels and kills over 70 species of insects, is effective for over two weeks, and contains sunscreens and coat conditioners for added protection. Using a combination of management methods is the best way to combat the variety of pest insects that plague the stable environment.