Mr Wilson

W.C. Stewart, The Practical Angler or the Art of Trout-Fishing, Edimbourg, Adam & Charles Black, 1857, p. 165

Mr Wilson in the Encyclopedia Britannica, and again in the Rod and Gun, states that the stone-fly come sot of the caddis or case-worm ; an aquatic larva, which is to be found plentifully in the bottom of most rivers, enclosed in a curious shell made of stiks and gravels cemented together.