This Skwala nymph still has a couple months left to go before hatching, but it's still a good representative of its species, which was extremely abundant in my sample for a stonefly of this size. It's obvious why the Yakima is known for its Skwala hatch.
Sclerite: An individual sclerite is a single, uninterrupted, hard plate of chitinous material, such as those that form the exoskeletons of arthropods. Structures are said to be sclerotized or sclerous if they are fully or partially covered by sclerites.
These other words reference the same concept: sclerites, sclerotized, sclerous, sclerotic.