Phyllis Ladyman, Water Boatman, Caddis Fly and Water Spider, Londres, Methuen & Co, 1966, pp. 12-16.
A caddis worm builds itself a case from bits of stick and stones. These are stuck together and lined with silk provised by a spinneret in its mouth. The caddis case its open at both ends so that water can flow through it. The head and legs stick out of the front and a pair of hooks holds on to the case at the tail end. The caddis worm never leaves its case. When in danger. Its head and legs are hard ans shiny, but its body is soft and so needs protecting. Caddis worms are vegetarians. As they grow they enlarge their cases from the front. Before turning into a pupa, a caddis worm fixes its case on to a root or plants in the water. It closes both ends of the case with silk to keep out intruders. For two or three weeks it is a pupa, still and helpless in its case…/… If you very carefully breal open a caddis case and put the worm in an aquarium, it will make a new case with bright-coloured beads or any other material it is given.