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Control of Insect and Related Pests of Livestock and Poultry in British Columbia

Horse and Deer Flies


Host: Cattle, Hogs, Horses, People

Description of Injurious Stages and Damage

Adults are medium to large flies sometimes referred to as "bull-dogs." Adult females pierce the skin and suck blood, causing great annoyance to animals, interrupting grazing, with loss of weight gain in beef cattle and reduction of milk yields from dairy cattle. Cattle and horses will often seek shelter in dense bush or in buildings to avoid horse and deer fly attack.
horse  fly image Horse Fly deer fly image Deer Fly

Summary of Life History

Life histories of our various species of horse and deer flies are not well known. Eggs are laid on stems and leaves of aquatic plants. Larvae live in the mud close to water, perhaps for a year or two, before pupating and emerging as adults. Adults are most active on warm sunny days.

Control Recommendations

No satisfactory protective sprays are available. Temporary relief may be obtained from repellent sprays. Darkened shelters or areas of deep shade into which animals can escape from the flies should be made available.


Black Flies | Bot Flies | Cattle Grubs | Face Fly | Hog Mange Mite | Horn Fly
Horse & Deer Flies | House Fly | Lice | Mosquitoes | Poultry Lice
Chicken Mite & Northern Fowl Mite | Sheep Bot Fly | Sheep Ked | Stable Fly | Ticks


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