Gerald Cox, Pond Life, New York, Michael Kesend, 1988, p. 42.

If you lie still and peer carefully into the pond’s shallows you may see what appears to be a tiny stick moving across the bottom. Close examination of that stick will reveal a  worm-like larva stage of the caddisfly Inside with its head and legs extented. The larva glues tiny sticks or other materials together to make a well camouflaged temporary home.