Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
The closed-off case opening suggests this one was already beginning to pupate, which also explains the unusual shape. I damaged it a little bit getting it out of its case.
This caddisfly was collected from Mongaup Creek in New York on May 6th, 2007 and added to Troutnut.com by Troutnut on May 18th, 2007.