Slate Drake Nymph

The Slate Drake belongs to the Isonychia genus of the Siphlonuridae family of mayflies and is one of the largest of the mayflies. The species name, bicolor, comes from its legs that are bi-colored. The common name “leadwing” comes from the lead color of the flies’ wings. The Slate Drake can be found in nearly all types of trout water and is one of the most important aquatic insects because they are abundant in many streams. Also, since the Slate Drake hatches can start in the spring of the year and continue through the fall season, these swimmer nymphs are readily available for the trout, indeed making them a staple in the trout’s menu.

Normally, the hatch will occur late in the afternoons and even extend into the evening. The Slate Drakes don't hatch in the water, but they crawl out of the water and onto the large boulders, logs, or banks and emerge into duns. You can see evidence of the hatch by finding their nymphal shucks on logs, banks and rocks. The nymphs prefer the highly oxygenated water and are found in the runs and the riffles of the faster flowing, freestone streams. They are expert aggressive swimmers and move fast as they migrate to the shallower water.