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Stable Fly
a stable fly

Personally, my most hated insect is the stable fly. This blood feeding beast is known by many names, most unprintable, but they are commonly referred to as ankle-biters, a reference to their favored feeding site, and sand flies, which refers to their habit of ruining a day at the beach. The name "stable fly" comes from their common occurrence in horse and livestock pens.

Due to recent moisture and poorly managed grass clippings and compost piles in urban centers, these flies are gaining quickly in numbers and are biting humans and pets in the backyard. The flies look much like a common house fly, but have a biting proboscis or beak which extends directly outward from the head. They are fast fliers, usually bite low on the leg, on feet and ankles, although any bare skin is fair game to them. On pets, especially dogs, they prefer to feed on ears and noses, drawing visible blood, and on livestock they tend to feed on lower legs, causing horses and cattle to stomp.

A damp organic matter mixture is what they prefer to breed in. In dog kennels and stables the mix of fresh manure and bedding straw is an ideal breeding area. Hundreds of stable fly maggots can sometimes be found in such unlikely places like the undersides of lawn mowers, so clean accumulated clippings clinging around the blade housing. Spreading and drying out of clippings and compost will reduce breeding. Also, proper composting methods, which maintain active decomposition which in turn generates sufficient heat, will stop fly breeding almost completely. Untended trash receptacles where food scraps are thrown can breed many flies, including house flies.

As usual, the best first step in control of insects is to eliminate the breeding areas mentioned above. Stable flies can go from egg to maggot to adults in less than 2 weeks in warm weather, so regular maintenance of breeding areas is critical.

For human protection, wearing long pants and dark socks will help deter bites. Deet products may help but these biters are very persistent. They laugh at sonic repellants, which don't work on anything anyway, are not attracted to UV light zappers, and sneer at citronella. Ointments that contain an insecticide are available from your local veterinarian or hardware store and these can be used to treat dog's ears and prevent stable fly feeding. Spraying shady vertical walls and vegetation where flies rest near kennels and buildings with a residual insecticide like permethrin will reduce activity as well. Residual sprays should remain effective for seven to 10 days if not washed off by rain or exposed to direct sunlight.

For livestock, along with residual sprays on buildings, area or knockdown sprays which are insecticides with short residual action can be applied as fogs or mists into fly inhabiting areas. The small droplets are effective in killing the flies they contact. These sprays are efficient if a number of horses are kept in paddocks around the stables. Some insecticides can be applied directly to animals with power sprayers if a number of horses are involved and if good holding and working facilities are available. If only a few animals are involved, the insecticide can be applied with hand sprayers, hand sponging or washing, or by aerosol or mist applications. Horses perspire and perspiration quickly breaks down insecticides, so almost daily treatments are needed for effective fly control. Insecticide applications should be concentrated on the head, neck, chest, legs, withers and back.
Good luck!

Stable Fly breeding ground
manure and bedding straw that is an ideal breeding area
Image of Keith Jarvi
Keith Jarvi
Extension Educator - Crops & Integrated Pest Management
Keith Jarvi has been with the University of Nebraska since 1979. He received a Master’s Degree in Entomology from North Dakota State University and a Bachelor of Arts degree in Biology from Gustavus Adolphus College in St. Peter, MN. His area of focus is Crops and Integrated Pest Management. As far as insect id he has seen a lot of interesting specimens, but there are always a few surprises every year.

Contact Keith at:
Dixon County Extension
57905 866 Rd
Concord NE 68728-2828
(402) 584-3819