Sparkle quill caddis pupa
Hook: Scud or pupa hook, sizes 10-18 (here, a size 10)
Thread: Green, 6/0
Abdomen veil: Light olive Z-Lon
Abdomen: Layer of green Z-Lon overwrapped with green turkey biot (here, overwrapped with green dubbing)
Legs: Brown partiridge feathers, tied in beard style
Wing: Sparse light dun Z-Lon
Antennae: Mallard splayed over top
Head: Dark brown dubbing
This is a pattern that is often attributed to Gary Lafontaine, but the originator is actually Mike Mercer. Gary developed the deep sparkle caddis pupa, along with many others.
The image shows two flies....the one on the left has a veil that's tied down rather snug to the abdomen, and the one on the right has the veil tied down a bit more loosely, allowing for more movement and potential trapping of air bubbles upon entry into the water.