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.
Some species of spiders actually live underwater, but they seem less common than those which live on land near the water. From a fly angler's perspective, then, spiders are mostly important as terrestrials.
Because of their relatively stable life cycles, there don't seem to be any points at which spiders become available to trout en masse. But they're undoubtedly a part of the mixed bag of summer terrestrials.
I have these Arthropod Order Araneae (Spiders) all over my property last weekend in West Kill NY. Are they poisonous? Do they live in the creek? Are they coming out of the creek to hatch because each one had a wed and egg sacks inside. They are big! Any thing interesting or warnings about these, I'd like to know.