What are those swarms of gnats or tiny flies in the air?

Image by dnnya17 via Flickr

Gnat is the common name for many small, winged insects in the fly family. Also called flies, midges and no-see-ums, many species look like mosquitoes and may form annoying swarms or clouds in the air called ghosts.

These are large mating swarms of adults. The swarms may occur for several days, especially after a wet weather. The tiny flies only live long enough to mate and lay eggs in or around water.

Most gnat species are considered an important part of aquatic food chains. After larvae hatch from the eggs, they live mostly in the soil decomposing plant litter. Larvae will feed for about 2 weeks before pupating in a cocoon near the soil surface. After 3-7 days the adult will emerge and live for around 8 days.

There may be several generations during the summer but they usually disappear in the fall. The last generation of gnats will overwinter as cocooned larvae in protected areas or organic matter.