When you see bugs "skittering" across the top of the water, just over the surface, maybe dipping slightly into the water as they go, it is generally a sign they are laying eggs.
The Egg Laying Caddis is designed to mimic just that.
Tied much like an Elk Hair Caddis with a bit of Chartreuse on the butt.
Even if you don't see caddis laying, the chartreuse butt can be considered a "hot spot" and often entices a fish when a standard Elk Hair Caddis won't.