Several types of flying insects, mostly members of the family of flies, have the ability to bite people. These bites are often painful and can be serious if the insect is a carrier of diseases, such as Lyme disease and, in tropical climates, malaria. You can identify the types of flying biting insects accurately by looking for certain features of these bugs.
Gauge the size of the flying biting insects that you encounter. Among the largest will be horseflies, which can reach lengths of a little over 3 cm in certain species. Deer flies will be smaller -- up to 1.5 cm long -- while mosquitoes are usually about 0.75 cm long and appear delicate. Gnats, such as the black gnat, are around 0.5 cm long.
Look at the features closely. Mosquitoes have a long sharpened proboscis that enables the females to deliver painful bites to unsuspecting animals and people. Black flies will often have a layer of fine hair on them, while deer flies and horse flies have large eyes in comparison to the head, which seem to bulge.
Note the time of day. Mosquitoe species are usually at their most active right before the sun comes up and in the period before it sets and immediately afterward. The black fly can bite any time during the day, and deer flies and horse flies also will look for victims during the daylight hours. Deer flies will circle around before alighting and trying to bite. Horse flies will usually seek out a spot on the neck, head or back to attack. Mosquitoes will go to any exposed skin that offers them a chance to land.
Inspect the bite. Horse fly bites, which can be very painful, can keep bleeding for many minutes, since the bug injects anticoagulant into the wound. The bite of a black fly will burn and itch. Mosquito bites will itch and cause a small rise on the skin, but are less painful than those of the larger biting insects.
Listen for the sounds that flying biting insects make. Mosquitoes will make a high-pitched buzzing sound as they pass by your ears. The deer flies and horse flies, despite their size, are usually silent in flight, which means they can land on you and bite before you are ever aware of their presence.