"Do you remember the time," my friend Steve began, "When I was fishing your Snowshoe Emerger on Skalkaho and had to take it off?"

I did, and Steve went on to recall the details. There was a blue-winged olive hatch on a cloudy day, about this time of year, and the fish were keying on the half-in, half-out of the water emerger stage of the fly.

Trout will do that with a blue-winged olive hatch. Every stage of the hatch will be on the water at once, and they'll eat only the flies in one stage of development and let the rest go by.