A more realistic stonefly imitation, the Stonefly Crawler is a good choice for trout in search of a larger meal.  The brown color pattern and medium size allows it to imitate several species of stonefly such as the Skwala Stonefly in western states.  Stonefly nymphs are most prominent in colder, highly oxygenated waters, and the long duration of this phase in the the insect's life cycle allows this pattern to be fished all year.  The tail of the fly is made with two golden brown biots, and the body is created by spiraling tan vinyl rib.  Brown dubbing is used to build up the thorax which also contains the six legs made using additional golden brown biots.  The wingcase is created using a dark hen feather.  Weight for the nymph is provided by the Flymen Fishing Company Nymph Head Stonefly Beadhead which also doubles as an extremely accurate head.  The fly rides hookpoint-up for optimal balance and movement.
 
Hook size:  3X Long Curved Nymph size 12.