There are many flying insects that look similar to mosquitoes and may be mistaken for mosquitoes. These insects can be annoying at certain times of year; however, unlike mosquitoes, they do not bite and cannot transmit disease. The District does not usually control these insects because they are not a threat to public health.

Crane Flies

Crane flies look like very large mosquitoes. Some common names for crane flies are ‘mosquito hawk’, ‘mosquito eater’,‘gollywhopper’ and ‘daddy-long-legs’. However, crane flies are not mosquitoes, don’t bite, and they don’t eat mosquitoes. In fact, most species of crane flies don’t eat at all as adults. They live only a few days, and die soon after reproducing. Crane flies found indoors can be swatted or captured and released outside.

Fungus Gnats

Fungus gnats live in dark places where they can feed on decaying vegetation and fungi. They sometimes emerge from the soil in houseplants, terrariums, or greenhouses. If they become a nuisance, you can control them using adhesive traps (available at most home improvement and garden stores). You can prevent fungus gnats by allowing the soil in houseplants to dry out between watering.

Midges

Midges resemble mosquitoes, but do not bite or carry diseases. However, they may be annoying when they are present in large numbers or come inside homes. Midges are most common in San Mateo County in spring and summer, and may be seen in large swarms with many individuals. They are attracted to light and may come indoors. Learn more about midges HERE.

Drain Flies

Drain flies (sometimes called moth flies, sewage flies, or filter flies) are small flies with fuzzy wings. They often emerge from drains in sinks, tubs, showers, and floors, where they lay their eggs in the organic residue on the inside of drainpipes. Adult drain flies can be seen resting on walls or surfaces near drains, or hovering near drains. The best way to control drain flies is to clean the infested drain with a brush or drain cleaner.

Caoborid Gnats

Sometimes called ‘phantom midges’, Chaoborid gnats are very small flies that appear translucent. Their larvae live in water and are completely transparent. Adult gnats can be seen in large swarms over lakes in the summer. They do not bite, but can become annoying when present in large numbers.

Dance Flies

Dance flies get their name from their erratic flight patterns in mating swarms. They are commonly found in swarms, sometimes above stationary objects such as shrubs or fence posts. Dance flies may be annoying outdoors, but do not usually come indoors.

Page last reviewed: December 28, 2023