Bright flashes from fireworks for the Fourth of July will thrill thousands of onlookers tonight.

However, an annoying pest could put a damper on evening activities. Here is what you need to know about midges, a mosquito look-alike that will be visiting outdoor parties this week.

Midges and gnats are common names for a large number of small, non-biting flies. Several of them look like mosquitoes and may form annoying swarms or clouds in the air, but they do not bite. Large mating swarms of adults often appear about dusk and may occur for several days, especially after prolonged wet periods. Many midges are attracted to light and may be a nuisance to homeowners.

These tiny flies do not feed. They only live long enough to mate, lay eggs and die. Egg masses are laid in the water of pools, containers, ponds, clogged rain gutters, and in some cases, in the vegetation of wet soil or seepage areas. Most feed on living or decaying plant matter and are an important part of aquatic food chains. Many species can survive in very stagnant or polluted water.

The life cycle usually takes four to five weeks. There may be several generations during the summer but these insects usually disappear with the onset of dry weather. Fortunately, problems are usually temporary and intermittent.

There are no good alternatives for control of adult midges. The best we have to offer is pressurized aerosol sprays containing pyrethrins. These are impractical for treating anything other than small areas. These products only kill insects that are directly hit by the spray mist — there is no lasting or residual effect. More midges will quickly enter the area after the spray has settled. The adults rest on vegetation and in the grass during the day, so an application of a malathion or Sevin (carbaryl) spray may reduce numbers.

Long-term control requires trying to eliminate breeding sites, wet areas or standing water. Often, however, this is not practical. Water should not be treated with any insecticide in an attempt to control the larvae or adults. The potential harm to the environment and wildlife is too great to justify an application for a temporary nuisance.