Difference Between Gnats & Fruit Flies

Gnats and fruit flies are commonly confused; they are both tiny, flying insects and it is difficult to distinguish between the two. They are related, both being from the same order, diptera. There are several different kinds of gnats and three types of fruit flies. The most obvious difference between the two is that in general, gnats feed on blood (either animal or human) whereas fruit flies feed on fruits and vegetables. Some gnats do feed on plant material but they are not commonly found in homes.

Gnats that Feed on Plant Material

• Most gnats are very small and the bites they inflict are harmless. Two types of gnats feed on and lay eggs in plants or rotting vegetable materials rather than eating blood; these are the gall gnat and the fungus gnat. The gall gnat lays its eggs on plants and the larvae then feed on the plant, which can cause great damage to the plant. The fungus gnat is less destructive, as it restricts its feeding to fungi and rotting plants.

The Buffalo Gnat

• The buffalo gnat is much larger and is more commonly known as the black fly. Black flies bite both humans and animals. These bites can be agonizing and swarms have been known to bite farm animals to death. However, the buffalo gnat is easily distinguishable from other gnats and from fruit flies because of its larger size. Most insect repellents work to deter black flies from biting.

The Mexican and Mediterranean Fruit Flies

• The three types of fruit flies include the common fruit fly, the Mexican fruit fly and the Mediterranean fruit fly. All three feed exclusively on fruits and vegetables. The Mexican fruit fly and the Mediterranean fruit fly are regarded as harmful pests because they lay their eggs in unripe fruits and the larvae then damage these crops. The common fruit fly is more of an annoyance, as it usually only feeds on ripe or rotting fruit.

The Common Fruit Fly

• The common fruit fly is of interest also because of its use in the study of genetics. Fruit flies are preferred by scientists because they reproduce quickly and easily. They also age relatively rapidly. Fruit flies are very common in warmer weather and climates and are easy to avoid by keeping fresh fruits and vegetables covered or refrigerated.