Midges are a type of small fly, often found near still or slow-moving water. Midges can vary from 1 to 10 millimeters and be seen in a range of hues, such as black, gray, olive green and even red. Midges have an important role as food sources for fish like trout and salmon that feed on them while they are hatching. The larvae of midges live underwater where they filter organic matter out of the sediment before pupating into adult flies which emerge onto the surface to mate. Some species also produce silk threads during their larval stage which help protect them from predators such as dragonfly nymphs.