The Thunder Egg is a simple fly pattern to add to your arsenal of steelhead flies. It's also great for salmon and trout. The fly was originally tied to target fish in the Rouge River system in Oregon but has been quite successful fished elsewhere on the western coast and on the Great Lakes tributaries.
I've modified my version of the fly by using brass eyes rather than lead and by using the Bug Shop Ultra Chenille instead of the Woolly Bugger chenille used on the original. https://globugs.com/products/glo-bugs-ultra-chenille
The Thunder Egg is weighted and was designed to be a sinker and to be fished in tandem with an unweighted egg. This was especially useful for fishing rivers where external weights were restricted.
You can tie this in any number of color combinations, but pink, red and oranges seem to perform quite well.
Thunder Egg Fly Pattern Recipe
Hook: Gamakatsu C14s #6-8
Thread: 8/0 (70d) Match to body
Eyes: Lead or alternative barbell
Tail: 8 strands pearl crystal flash
Body: Antron chenille or Ultra Chenille (Bug Shop)