Allow the fly line to sink until straight up and down and then begin a very slow hand twist retrieve right to the surface of the lake. At other times trout will take the pupa just under or in the surface film. The angler will see subtle head and tail or slow bulging riseforms in this situation. Shorten your leader to approximately 4 meters, grease it well to make it float and fish a pupal pattern as close to the surface as possible. Trout will sometimes feed on the egg laying adult chironomid.
Females typically return to the lake in the evenings when winds are down and darkness approaches.
In most situations, individual trout will show a distinct movement or feeding pattern which will allow you to anticipate its speed and direction of travel. Cast an adequate distance ahead of the fish with a floating adult pattern. As soon as the fly hits the water give it a couple of long fast strips so that it forms a wake on the water, then let it sit for a few seconds before repeating the fast strips. Float tubers or pontoon boat anglers should have one anchor out the back and then use their swim fins to control unwanted sideways motion. Also, keep your rod tip close to or touching the water during the retrieve thus providing as straight a line connection between rod, fly line, leader and fly.