Thanks for the http://www.west-fly-fishing.com/ento...aneflies.shtml link. That's as good a description of the bug lifecycle as I've seen. It also explains and confirms the notion that the larva and egg laying adult are the main stages of interest to the angling.
I'm sure craneflies vary quite a bit in size and coloration, but here's an adult / dry fly pattern that quite a few folks here in the driftless (SE MN / SW WI / NE IA) really like:
http://www.graygoatflyfishing.com/20...ead-crane-fly/. One point worth noting is the emphasis on the legs as a key trigger aspect.