These tiny flies cause large problems with their biting and blood feeding habits. They are far better known by the name No-see-um, given for their habit of biting and leaving and not being seen by the person who felt that bite. Over 600 species occur in North America. The larvae live in most wet settings, including sand and soils near fresh and salt water habitats, rotting logs, and decaying vegetation, and this diversity makes their control at the source nearly impossible in most cases. In some areas they may be vectors of parasites to poultry, livestock, or possibly to humans. Because of their tiny size they often are able to pass through typical window screens on homes. Their numbers around aquatic areas and beaches can sometimes be extremely high and their highest activity is during the summer months.
Because of the inability to control the source of the problem with insecticides, non-chemical means are most important. If the wet locations where the larvae are living can be dried out or drained it will be helpful, and this includes piles of rotting vegetation such as thick mulch. Where the midges are a problem windows should be fitted with screens with a mesh small enough to exclude them. While outdoors people should be encouraged to wear long sleeves and long pants as well as an effective repellent. Fogging with pyrethrum may provide temporary relief on a localized basis.