Midge Life Cycle
The midge life cycle is a complete metamorphosis with four distinct phases: egg, larva, pupa, and adult. Adult midges lay their eggs over water, and the larvae emerge and thrive in many water types, but especially in slow water with a silty, muddy bottom covered with debris and aquatic vegetation.
To be a proficient midge fisherman, you need a range of fly patterns that imitate every stage trout prey upon. You need to know what fly to use, and when to use it. Things can change suddenly during a midge hatch, or combined midge hatches, especially on productive water where large trout have the luxury of targeting specific stages of specific insects. Sometimes you’ll tear up the river on a #20 red larva imitation, and then suddenly the fish switch to dark brown #24 pupa.
Even the best anglers sometimes overlook the importance of midge larvae. Midge larvae are long and slender with a uniform profile. The best imitations are nothing more than thread twisted to create a segmented look wrapped on a curved hook. Anything with a bead or with a pronounced thorax has the wrong profile.
Think long and slender for midge larvae, short and squat for midge pupa. The pupa’s thick thorax contains the adult’s developing wings. Make sure when you tie these that you use a short shank hook and the body is really segmented with a large head. See this example of midge pupae.
When midges begin to emerge, their budding wings become prominent, and they sometimes carry gas bubbles that trigger trout to feed. This phase of the transformation has been studied
extensively by some very good anglers who have developed deadly imitations. Rim Chung’s developed the RS2 for finicky South Platte trout and has been widely adapted everywhere .
These flies are best tied on a curved hook with some sort of representation of the wing buds and flash to imitate the gas bubble.
As with all midge fishing, fly size is the critical element, followed by the shape and color in that order. There are many excellent patterns out there to choose from. I have had good success with just a thread-body fly, two turns of grizzly or light dun hackle and a clear medallion sheeting wing. Make sure that you have these in black, olive, gray and light yellow.