Deep Sparkle Pupa grey - Larva & Pupa. The Grey Deep Sparkle Pupa is one of the top flies known to fish right before a large caddis fly hatch. The reasoning for such a exclamation can be explained rather simply. Directly before a large caddis fly hatch some pupa will drift out early from the hatch and just float lazily in the deeper water. After fishing the Deep Sparkle Pupa Grey many times myself, I can fully say that this fly was made to perfection for its purpose. Trout hungry for the caddis hatch to begin will grab this fly in an instant.