One of the most important things to a choosy trout is the one thing my close-up pictures can't show: motion. Fly tyers imitate motion by using lively materials, and fly anglers imitate it with subtle rod-work, but both need to understand how the real critters move.
Most of these were shot long ago with an ancient digital camera, but I'll be adding higher-quality material this year.
In angling books, Leptophlebia mayfly nymphs have a reputation as poor swimmers. In reality, they're very adept swimmers, much moreso than most other mayfly nymphs categorized as "crawlers."
Water boatmen are excellent swimmers, and you can see here how they use their oars to push themselves through the water, a motion easily imitated by the fly fisher.