Midges come under the Diptera family which include:
Flies, Gnats. Mosquitoes, Midges, Sandflies, Crane flies, Sheep keds, Maggots, True flies and Mosquitos.
There are many different shapes of True Flies. They are soft-bodied insects, most are fairly small (less than 1.5 cm long) but a few can be larger (up to 4 cm! Eeeek). Adult flies have only 1 pair of wings, unlike other insects. The second pair has evolved into small balancing organs that look like little clubs. Adult flies feed on liquids and have either thin sucking mouthparts (like Mosquitos) or sponging mouthparts, a tube with wider sponge at the end (like Flower Flies and House Flies). Most adult flies have large eyes, to help them see when they are flying. Many adult flies look like wasps or bees.
Flies are one of the most diverse groups of insects. There are over 150,000 species known from around the world, and there are certainly many still undiscovered. In the Great Lakes region there are probably over 2,000 species.
True Flies have complete metamorphosis. Adult female flies lay eggs, and then small larvae hatch from the eggs. The larvae are often worm-like, and do not have jointed legs. They molt (shed their whole skin) several times as they grow. Then they transform into a pupa, which is a resting stage that transforms into an adult.
Some flies are imporant pollinators. Many fly larvae are part of the natural ‘clean-up squad’, helping get rid of dung and dead animals. Flies are important food sources for many other animals.
The biggest benefit from flies comes from the parasitic species. They attack caterpillars, grasshoppers, and other insects that eat our food plants. Some flies also help pollinate plants that we grow. Flies are also important food source for other animals that we value, like fish.
How do they communicate?
Flies use vision more than most insects do. They also sometimes detect the vibrations of wingbeats. Like all insects, they use their sense of smell a lot.
So now you know.
More on creepy-crawlies: http://www.discoverlife.org