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Saturday, Apr. 30, 2016

Ask the Vet

Monday, July 11, 2011

Fly control has become an important component of livestock production across the nation. When it comes to prevention, it is beneficial to know your foe.

Horse fly (Tabanus sp.) and Deer Fly (Chrysops sp.)

Horsefly: 25mm long, Deerfly: 6-10mm long

Strong fliers and females are biters

Deposit eggs (100-1000 at a time) in wet/moist habitats

Control: Animal - pyrethroid products weekly, but control is poor.

Environment - not effective since these flies do not rest on any one surface

House fly (Musca domestica)

6-9mm long, does not bite

Deposit eggs in fresh manure, garbage, lawn clippings, etc.

Rest on fences, buildings, trees and shrubs often in the sun


Animal - usually not necessary since do not bite

Environment - remove manure, baits, pyrethroid sprays to resting sites

Stable fly (Stomoxys calcitrans)

Piercing bite

Deposit eggs on feed, decaying matter, old manure, moist hay

Cluster around feet and legs of livestock

Rest on shady surfaces such as fences, feedbunks, buildings and vegetation


Animal - pyrethroid sprays

Environment - clean around feed bunks, pyrethroid sprays to resting sites, fly baits will not work

Face fly (Musca autumnalis)

Looks like house fly but slightly larger

Can travel several miles

Feeds on cattle secretions such as tears, saliva, nasal discharge and blood commonly found on nose, face and backs of cattle

Deposit eggs in fresh manure

Spend less than 5-10 minutes per day on an animal, remainder of time spent on shaded vegetation

Vector of pink eye (Moraxella bovis) physically scratch the eye with biting teeth

Control: Animal - insecticide sprays on face, mineral feeders with pyrethroid (de-lice) lining cover

Environment - impractical since must remove fresh manure

Horn fly (Haematobia irritans)

Small 4mm long

Painful bite can result in weight loss from irritation

Lay eggs in fresh manure (3 minutes old) and spend rest of life on backs of cattle

Highest numbers on bulls because testosterone attracts the flies


Animal - flies highly resistant to pyrethroid ear tags, best result is rotation of insecticides topical pour-ons provide control for 1-4 weeks depending on weather and product used

Environment - not useful.