Spiders

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 (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.).

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 (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.).