Thomas Frederick Salter, The Angler’s Guide Being A Complete Pratical Treatise on the Angling, Londres, T.Tegg, 1815, p. 169.
..by the names of cad-bait(*), case-worms, rough-coats, &. Which were formerly used by angling for Roach, Dace, and Chub ; but in respect to their value as bait for fishing, compared with what the modern angler uses, they are not worth naming or describing, yet are extremely curious as a natural production.
The cad may be found on the margin of small rivers, (the banks of the New River, and the Lea abound with them) adhering to the bank sides, or a little below the surface, and sometimes on the top, during the spring months. This insect is about three quarters of an inch long, enclosed in a rough case, the size of a tobacoo-pipe stem, and has the apppearance of a small piece of decayed stick : as the weather becomes warm, they break through the case, and are a complete fly.
(*) Cads, cadis, or case-worms , or magots, may be kept and scoured in a box or bag, in damp house-sand ; but they are really not worth the trouble of getting or preserving while gentils can be procured : when they are changed into a fly some use them sunk a foot in the water, by putting a small shot on the line, and wilk sometimes take a fish in the manner.