The Stone Fly is number 3 of the 3 most important flies to the Fly Fisherman. This fly lives in the cooler mountain streams that have a high oxygen content and needs flowing water to live.

Fish have two opportunities to dine on these large insects, once when they emerge from the nymph stage and crawling onto land and again when the females take to the water to lay their eggs.

The Nymphs crawl out of the water onto a stone, log or other vegetation and remain long enough to dry out and climb out of their nymph case. They will then crawl or fly into the nearby vegetation.

Most species of the Stone Fly don’t fly very well so most of their travel on land is done by crawling. Stone Flies can live for several weeks, during which time they will mate and the female will lay her eggs.

The male attracts the female by drumming his abdomen on a tree branch.

After mating the female will return to the water to deposit her eggs on the water in clusters or will crawl under the water and deposit the eggs on vegetation on the bottom of the stream.

Stone Flies do not swarm and do not fly very well, so the egg laying process consists of a single female thrashing about on the surface of the water depositing her eggs and usually attracting several trout to the scene of the commotion. There is some discussion that this behavior explains why a Steelhead will take a dry fly after it returns to fresh water. Adult Stone Flies usually die during the mid to late summer.

Some Dry Fishing Fly Patterns that imitate the Stone Fly are: