Hook: 2X- or 3X-long wet fly hook, sizes 8 to 4.
Thread: Olive 6/0 (140 denier).
Bead: Small black bead.
Body: Brown Crystal Chenille.
Head: Green Antron dubbing.
Legs: Brown hen hackle fibers.
Pick up a few rocks from your local trout stream to study the immature aquatic insects. The chances are that you will find at least a few small cased caddisfly larvae. These wormlike insects build their protective cases using bits of leaves and other matter. Knowledgeable anglers know that trout eagerly ingest these insects, cases and all. In recent years, cased-caddis imitations have become my go-to patterns when fishing nymphs. Although many cased-caddis patterns are difficult to make, the Crystal Larva is easy to tie, and it catches fish.