Horse flies, in general, are attracted to dark shiny objects and carbon dioxide. Horse flies are most active in humid and warm conditions, that’s why they are mostly found near beaches and lakes.
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Horse flies are one of the most ferocious breed of flies. Unlike a common house fly, horse flies have cutting and tearing type mouth parts. They are a nuisance for livestock, horse flies (particularly female ones) land on the body of cattle and bite them to draw their blood.
The horse fly is easily identified by its dark grey body and large green-metallic eyes. The horse fly can also be spotted by the dark black markings on its transparent wings. Horse flies are very strong fliers, persistent in attacking livestock and equine with a severe bite.
Horse flies torture horses and other animals, including humans, with abandon. An accidental but long-standing remedy that horse flies seem to hate is Avon’s Skin-So-Soft bath oil. Vinegar — white or apple cider — is another. Each is safe for animals or people; just pour in spray bottles and apply.
The best way to minimize the risk of being bitten is to stay indoors, since these insects prefer to remain outdoors. Wearing heavy clothing and protective hats can make it more difficult (although not impossible) for a horse fly to bite.
Horseflies are most active in hot weather, mostly in summer and autumn during the daylight hours. Most species also prefer a wet environment, which makes it easier for them to breed. Eggs are generally laid on stones close to water or on plant stems or leaves.
A fact sheet written by Lee Townsend, extension entomologist University of Kentucky College of Agriculture, states that manmade chemical repellents such as DEET “can provide several hours of protection” from deer flies and horse flies.
Once the horse fly is locked in, it eats the blood from the skin. This bite can cause a sharp, burning sensation. It’s common to experience itchiness, inflammation, and swelling around the bite area. You may even develop a bruise.
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In both species, only the females bite to feed on blood; the males feed on plant products. The insects leave saliva under the skin as they feed. The saliva briefly thins the blood and prevents it from clotting so that it is easier to feed on.
It sucks blood for food and to reproduce, he said, and should be seen as part of the biodiversity of the planet, albeit an annoying one. And birds do eat horseflies, so the insects do have some utility, Gammelmo says, even though it’s not known how much of the diet of a bird the fly represents.
However, unlike mosquitoes, which puncture their victim’s skin and suck blood through their mouthparts, horse flies are equipped with slicing stylets. Using these tiny blades, horse flies cut open their victim’s flesh and drink from the blood that pools in the wound. These bites can result in irritation and swelling.
Horse flies are not without predators – birds eat both adults and larvae; nematodes and wasps parasitize the larvae, and adults are captured by solitary wasps to provision their egg caches and by spiders.