Types of Flies
With over one hundred and fifty thousand Diptera species, divided into over one hundred families, a proper categorization of different types of flies would necessarily be an encyclopedic endeavor.
A less systemic approach to Diptera often begins by thinking about them in terms of their relationship to humans.
Many people, for example, want to know about poisonous flies. In fact, there are no poisonous flies in the sense that these insect produce and inject venom as do some spiders.
It's more accurate to think of flies as disease spreading pests that pick up bacteria and viruses from many different sources, and then spread those bacteria and viruses during the course of their every day existence. Mosquito transmission of West Nile virus for example, presents an ongoing challenge to public health officials.
Other flies such as horse flies, deer flies and snipe flies are rightly labeled as biting pests.
Notwithstanding the pest label, many fly families can be considered as beneficial insects that pollinate plants and prey on insect pests.
Given the fact that fly identification is not everyone's cup of tea, identifying a fly to the family level might be considered an accomplishment.
Identifying some families are easier than others. The long legs and thin bodies of many crane flies makes them easy to identify.
At the family level, may horse fly species can also be relatively easy to identify, especially the females with colorful eyes. The first picture highlights horsefly eyes.
Deer flies, in the same family as horse flies, can also be reactively easy to spot. The female eyes are often equally colorful, however, they ten to be spotted, rather than lined like the female horse fly as shown in the second picture.
Nonetheless, with over seventy different horse fly species and approximately sixty different deer fly species, identifying and specimen down to the species level will take a bit of detective work.
Members of the family Tachinidae, or tachinid flies, like the specimen in the first picture, are known for the large, often coarse hair on their bodies.
Thin bodies and a face that appears to be filled with whiskers serve as clues for identifying robber flies.
Some fly families such as bee flies and syphrid flies can be confusing to identify. They are mimics that resemble bees and wasps. When confused, the easiest thing to do is count the number of wings. Flies have two wings, hence the name diptera, which means two wings in latin. Bees and wasps have four wings.
Other fly families share many outward physical characteristics, making a microscopic examination of a specimen necessary for identification.
The house fly, for example, is a term that often applies to any fly found inside the house. Technically, the term applies to species in the Family Muscidae, and a close of look at a species will reveal plumose (feathery) antennae, as opposed to the aristate antennae on a similar looking flesh fly.
The links in the box on the right point to pictures and descriptions of a representative sample of fly families and species commonly found in backyards, fields and forests around the United States.
Special attention is given to identifying species in two families of beneficial flies, the often large and hairy tachinid flies and the bee and wasp mimics in the family Syrphidae.
One final note: A variety of insects have the name fly attached to them. Fly fishing, for example, would not be the same were it not for mayflies, alder flies, caddisflies and stoneflies. The insect world is huge, and these types of flies constitute entirely different insect orders, rather than the members of the diptera order presented here.
© 2005-2013 Patricia A. Michaels