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Black flies and midges are out now

Jeffrey Hahn, Extension Entomologist

There are two types of flies that are being commonly seen this spring: black flies, also called gnats, and chironomid (ki-ron-OM-id) midges. Black flies can inflict painful bites to people, while midges are just nuisances.

Black flies are small but many people think they inflict a more painful bite
than mosquitoes.  Photo credit: Jeff Hahn, Univ of MN Ext.

When do black flies bite?

Black flies are stout, humpbacked, dark-colored flies. The larvae live in rivers and streams. The adults are good fliers and can be found miles from where they emerged. They commonly bite people on exposed skin during early morning and early evening as well as on cloudy days.

Fortunately, black flies are not known to transmit diseases to people in Minnesota. Even if they don’t bite, they can still be annoying by flying around a person’s face.

It is challenging to avoid black fly bites. Here are some helpful tips:
  • When possible, avoid the times when black flies are most common. 
  • When you are out, wear protective clothes to cover bare skin including long-sleeved shirts, long pants, socks and shoes, and hats. 
  • Wear something on your head as black flies love to bite around the hairline. Although black flies can be active throughout the season, they are most common during spring.
  • Unfortunately, repellents, like DEET, are not consistently effective against black flies; but their use is still probably better than nothing.
Chironomid midges don't bite but often occur in large numbers,
which can be annoying. Photo credit: Jeff Hahn, U of M Ext.

The myth of the biting midge

Chironomid midges are also common around Minnesota. They are mosquito-like in appearance; males have feathery antennae. Despite that, they do not bite. The larvae live in water but the adults are not strong fliers so it is common to see them on foliage near where they emerge.

These midges commonly fly in large clouds in order to mate. Anyone around such a cloud can get midges in their faces and their food and drink. Annoying but not the end of the world.

Even though these midges do not have chewing mouthparts, they have been suspected of damaging turf and garden plants. Fortunately, they are incapable of injuring plants.

Midges are short-lived, usually not lasting more than a week or so. While there are different species that can occur at different times of the year, most hatchings are not noticed by people. There is no control for midges, ignore them (as best you can), and they will go away on their own.

See BugGuide for information on chironomid midges.

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