No flies on you
08.23.10
No flies on you
By Betsy Wieland, Agriculture Extension Educator, Hennepin County, University of Minnesota Extension
There’s nothing like having your horse dance around you when you’re trying to clean his feet because he’s being harassed by biting flies. There are two categories of flies around horses and there are steps you can take to make your horse more comfortable.
The stable fly.
Filth flies are the first type of fly. They include stable flies and house flies. House flies are not pests to horses, but do enjoy coming indoors. Stable flies bite hard, and often horses’ and people’s legs. They breed in moist, warm environments with decaying plant material like old hay piles and manure piles. Ideal temperatures for them are 70-95° F. They are both active during daylight hours.
Controlling them is best done by controlling breeding ground, as a female can lay 50-150 every few days. Clean up old hay, compost manure, and fix leaky water fixtures to reduce habitat. Some people have luck with fly predators, although research is inconsistent on their success. These predators are small wasps that lay eggs in the fly maggots and parasitize the maggot. Fly traps will help to some degree and are fairly satisfying, but until you reduce the breeding areas, more flies can move back into the area.
Aquatic biting flies are the other type of flies that pester horses. These include black flies, horse flies, deer flies, and mosquitoes. These are much more difficult to control because they develop in wetlands, which cannot be managed, and the adults can travel several miles from where they hatch. Horse flies and deer flies are also active in bright daylight and rarely venture into shady areas, while mosquitoes are active at dusk into the night or in shady areas.
Since we are unable to adequately control their breeding ground, for the daytime aquatic flies, avoidance is the best policy. Give the horses access to shady areas during the brightest part of the day. Let them determine the most comfortable spot to be.
Since mosquitoes are most active in dusk and evening hours, horses can be protected from them by housing them indoors in the evening behind screened doors and windows and/or with fans. Mosquitoes breed in shallow, still water with decaying leaves and algae. So on-site control of mosquitoes can include cleaning water tanks, turn over buckets, drilling holes in tire swings, etc.
As for fly sprays, they can be applied to the horse, or the premises. Pyrethrum and resmethrin fogs can be used indoors and outdoors on fly perch areas (look for fly specks) but are temporary solutions as they break down quickly. Pyrethrum contains pyrethrins, which are extracts of a type of chrysanthemum. Resmethrin is synthetic version of pyrethrin. Many sprays applied to horses will have these as active ingredients but they tend to work only for a few hours. Pyrethroid and organophosphate insecticides are longer lived, and are used for premises sprays, but not applied to the animals. Without managing the breeding ground of the filth flies, these will have limited use.
In conclusion, some flies can be controlled with site management and good sanitation, while a duck and run method is needed for others. For more information, see this factsheet:
http://www.extension.umn.edu/distribution/livestocksystems/DI8537.pdf , or contact your veterinarian or your cooperative extension service.
Tags: aquatic biting fly, black fly, deer fly, filth fly, horse fly, house fly, mosquito, stable fly
