A.R. Mattews, Freshwater fishing , Londres, Cassell & Co., 1920, p. 22.

The caddis grub’s tube-shaped  « house » or case is a wonderful structure composed of bits of dead twig, straw, weeds, minute shells, sand, etc.. and is very neatly and cleverly placed together by the aid of some glutinous substance. The « cad », as it is familiarly know to anglers propels the case along with its feet which are outside, but when danger threatens, its head and legs quickly disappear inti the case; It is generally met with in the spring and early summer, and on searching likely haunts the angler can soon secure enough cads to last him for the day’s fishing.
Cads are also sold at some of the tackle shops.