Chironomids are non-biting cousins of mosquitoes, which are prominent in most lakes, worldwide. Possibly as many as 10,000 species exist. As such, chironomids are a natural food source for many species of fish, including trout, bass, and sunfish. In Europe and North America, they are a favorite topic for fly tyers and fly anglers, especially the ones who fish for trout in cold lakes. Because of their diversity, chironomids hatch nearly every day almost everywhere there is standing water. They are one of the most reliable hatches. During the spring and fall months, several species will stretch the hatch into most of the daylight hours. Colors and sizes may change as the day progresses. It pays to be observant, as trout selectivity can change with the hatches.
Black
The Stalcup's Chironomid is tied with tiny wings, which are just starting to emerge from the wing case. For this reason, the flies are designed to be fished near the surface of the water. Watch for rising trout and cast to risers. Black is always a good searching pattern, unless you can observe that the hatching insects are a different color.
Olive
Chironomids come in a variety of sizes and colors including black, brown, olive, and red. Flies in these colors and in sizes #14 and #16 will match most of the important hatches in lakes of North America. The most popular colors for flies are black or red, with black being slightly more popular. Olive is a sleeper color, especially in weedy lakes where chironomids consume a lot of chlorophyll. Many times, if you are getting refusals on other colors, an olive fly will turn the trick. Often these lighter-colored chironomids are smaller sized.
Blood Red
Some lakes have prominent hatches of red chironomids. These insects contain hemoglobin, much like our own blood. Larvae of these insects are known as blood worms. Fish can become selective to these brighter colored flies.