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.
This spinner was the only member of its species I saw all night during an incredibly thick and tricky mixed hatch on Penn's Creek a few days before the real start of its famous green drake hatch.