Caddisfly Species Amiocentrus aspilus (Little Western Weedy Water Sedge)

This species produces fishable hatches across the West.

I encountered them in mid-August on the Henry's Fork, mating in thick swarms up and down the bank of the Harriman Ranch reach. However, millions of Tricorythodes mayflies found their way onto the water that same morning and it's unclear if the trout were seeing and responding to the caddisflies at all.