Deep Black Stonefly is an all purpose Fly Pattern that is very good for Trout and this happens to be a Beginner Fly Pattern.
This Beginner Fly Tying Tutorial is by Jim Misiura, and he does a very good job at demonstrating (and explaining) how to tie up this Black Stonefly.
The Deep Black Stonefly is a definite Pattern that you need in your Fly Box, no matter what species of Fish that your targeting.
Stoneflies are a regular diet for fish because they seem to be in all bodies of water, be it Rivers, Streams, Creeks, Ponds, or Lakes.
This Stonefly can be tied in other colors (Gold, Brown, Olive) as well as Black and is a Nymph that you definitely want to carry with you.