Last night I tied up this fly. For some strange reason...I thought of a friend of mine while I tied the final knot. This fly is called the "Ramback" (his name is not actually spelled like that but I think it's better for the fly). This is basically a Pat Dorsey Mercury Midge. Pat is probably the best guide in Colorado. Pat ties his with gray thread and then segments the body with copper wire. I used white thread and green wire. This fly represents the nymph stage and the bead is the key to the whole thing. Some midges will suspend themselves right below the surface of the water before hatching. These things then swim down about 6 inches and then come back up to the surface. They repeat this cycle before emerging. Each time they hit the surface, a little bit of air gets trapped in the shuck. I don't know why they do this. Perhaps the air helps them break free of their exoskeleton's? Whatever the reason is...the air bubble on their upper back looks just like a little drop of Mercury in a thermometer. My good friend is a science teacher. I think he'll get it.