W.C. Stewart , The Practical Angler or theAart or Trout-Fishing more particularity applied to clear water, Londres, A. & C. Black, 1907,p. 152.

Mr Wilson in the Encyclopaedia Britannica, and again in the Rod and Gun, states that the stone-fly comes out 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 sticks and gravel cemented together. But we believe this distinguished naturalist to be in error ; the caddis worms, or cod bait, as they are usually denominated, are to bre found in abudance up to the beginning of August, long after the last May-fly…