The actual presence of midges on the water is the best clue that trout are rising to them. Lakes, ponds, and sloughs are rich with midges, which are near the top of the list of insects that rising trout might be feeding on. On streams the importance of midges usually varies with the season. The summer months bring on caddis, mayflies, and stoneflies, moving midges to near the bottom of the list of favored trout insects. From late fall into the spring season, however, midges may be the only aquatic insect emerging.
Midges are two-winged flies that come in a variety of sizes and colors.
They can emerge on all waters any time of the day and season. Be prepared with imitations of pupae and crippled adults and you will catch trout on midges. Rarely will a fly fisher encounter activity of any terrestrial insect concentrated enough to cause a rise of trout. Grasshopper activity is strongest during the heat of the sum' mer months, but I've taken trout from May through November on hopper patterns. Though hoppers are most prevalent in August and September, the fact is that they're often present on western waters for much longer.