Tabanidae include both Deer Flies and Horse Flies. Deer Flies are smaller than Horse Flies (1/2” long). Their wings are tinted smoky brown or have dark patterns. Their thorax is greenish-yellow with dark stripes. The eyes touch each other on the top of the head in males and are separated in the females.
Horse Flies are like Deer Flies but much larger and heavier-bodied (1/2”-3/4” long). Their wings are clear and their thorax is usually brownish-grey striped. The abdomen may be orange and black patterned or similar to the coloration of the thorax.
Deer Flies are strong fliers going many miles. They are painful blood feeders and frequently become serious pests of livestock and humans. They are also known as “cedar flies” in parts of the United States. The males are found on flowers and feed on nectar and pollen. The females may be seen circling your head.
The larvae of Deer and Horse Flies are semi-aquatic and are mostly found in moist soil along the edges of ponds, dug-outs and cattail areas of some ditches.
The Horse Fly, like the Deer Fly, is extremely difficult to control. They cause intense pain at the site of the bite, which is very annoying to livestock as well as to people. Unlike the Horse Fly which lumbers around you before biting, Deer Flies zoom in, circle fast and bite quickly.
If repellents or insecticides are used, some decrease in feeding may occur but many will still feed.
Avoidance of heavy feeding areas may be the best preventive strategy for this pest. Fly Predators, House Fly traps and baits have no impact on these pests. An effective trap is the H-Trap that is specially designed to attract these species plus Yellow Flies and Greenheads. One H-Trap will cover a 5 horse outdoor paddock of about 2.5 acres.
Dr. Bill ClymerFort Dodge Animal Health, Dr. Roy EllisPrairie Pest Management, Dr. Kevin FloateAgriculture and Agri-Food Canada, Dr. Robert M. Miller, DVM, Dr. William QuarlesBio-Integral Resource Center. All illustrations 2006 Dr. Roy Ellis.
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