The Klinkhammer fly pattern is very popular among fly fishing enthusiasts. Dutch angler Hans Van Klinken tied this fly to imitate emerging caddis flies. Emergers are becoming more and more popular with anglers due to their extreme effectiveness. Emerger hooks are designed to have the bottom half or more of the hook sitting in the water. The parachute part of the top helps it to stay afloat.
Presentation is everything when using an emerger. You want to make your fly look as natural as possible to increase your chances of a strike. Cast your fly line and leader a little upstream of where you think the fish are and let it drift down with the natural current. Flick your line upstream as needed to make sure your drift stays natural.
The olive body on this pattern is perfect for those dark days. Remember the dark colored hooks are for dark days and bright flashy flies are for clear and sunny days.