The Cooper Bug is an easy-to-tie and highly effective pattern in southern freestone streams this time of year. It’s an old pattern of disputed origins. The Cooper Bug is generic in nature, trout can mistake this nymph for lots of different "stuff" including caddis, Iso’s etc. Plus, flies tied with peacock herl just seem to catch fish.
Hook: #14 Mustad 38941
Body: Peacock herl
Back/tail: Caribou hair, trimmed at the eye of the fly