It can be many sizes and colors, but predominantly one will find brown, size 12 to 18 nymphs. Clingers cling to the underside of rocks, and are more predominant in flowing water. When mayflies hatch, almost all species rise through the water column and provide classic hatch fishing, with emerger and dry flies. Adult mayflies have upright wings, thin bodies, long thin tails, and short antennae. It is the spinner stage that mates and lays eggs.
Many mayfly species swim below to lay eggs, and so offer wet-fly fishing.
These dead spinners have spread-out wings rather than upright wings, and so the patterns used to imitate them are different. In the caddis family, the longest underwater stage is the larva, unlike the mayfly. A caddis larva essentially looks like a maggot, with a soft, often off-white body with no legs on it, usually a dark head, and with a couple of short short legs right behind the head that it uses to hold on to rocks with. In many caddis species the larva build cases out of sand, pebbles, sticks, and other debris, and the only thing that ever sticks out of the case is their head. Others are free-living.