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.
These larvae were all over the submerged rocks in a small mountain stream in the Washington Cascades, tightly adhering to the rocks in their flat, half-disk-shaped cases.
This true fly was collected from Mystery Creek #249 in Washington on July 25th, 2019 and added to Troutnut.com by Troutnut on July 27th, 2019.