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Common flies around horses and how to control them

Quick facts

  • You can best control filth flies by managing moist organic debris sources:

    • Manure and bedding

    • Rotten feed

    • Mud

  • Traps, stingless parasitic wasps and insecticides for filth flies are most effective when combined with debris management.

  • Managing water sources and providing your horse deep shade or housing can best protect them from aquatic biting flies.

  • Work with a veterinarian to have your horse vaccinated for mosquito transmitted viruses.

Horse with flies around its eye
Flies can bother horses and spread disease.

Flies are a natural part of keeping horses. Filth flies and aquatic biting flies are the main concerns in Minnesota. Understanding what these pests are and how they live and breed can help horse owners limit their fly pest problems.

How do flies affect horses?

Flies can harm horses by

  • transmitting viruses and diseases.
  • causing welts or skin irritation at bite sites.
  • causing hoof damage from excessive stomping.
  • prompting overall discomfort as horses try to avoid them.

Horses usually swish their tails or stomp their feet to get flies to leave. They may also try to move their heads toward their bodies and limbs or twitch their skin to get rid of them.

Filth flies

Filth flies develop in moist organic debris such as:

  • Aging feces

  • Soiled animal bedding

  • Rotting feed debris

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Aquatic biting flies

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Authors: Roger Moon, entomology professor emeritus, College of Food, Agriculture and Natural Resource Sciences, Betsy Wieland, Krishona Martinson, Equine Extension Specialist and Rachel Mottet

Reviewed in 2023

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