Once late spring rolls around, it’s time to tie on A Slate Drake Nymph. Slate Drakes are unique in that they don’t emerge through the water column like other mayflies. Rather, they crawl out of the water onto rocks and logs where they break free of their nymphal shucks. This pattern has the split back of an emerging nymph, which is why trout go crazy for it when Slate Drakes are on the move.