H. E. Towner Coston, The Swift trout: a tale of trout in two rivers, Londres, Collins, 1946, pp. 43-44.

As they grew they attacked anything that moved , young caddis, shrimps, and tiny delicate snails. But, if they carelessly expoe themselves, they in turn fell victims to the trout.
Many of the sedges which had fluttered over the surface during the summer had laid their eggs, and thse were hatching into tiny caddis grubs. These little naked beasts went busily on their way collecting their winter homes, to serve not only as a protection throughout the coming winter, but as places Where they might rest, pupate, and eventually develop into fully fledged adult flies in the following year. Some wee collecting tiny grains of sand, and other larger and more powerful one seized upon luckless snails and old snail shells with which to form their roofs and walls. Every morsel, collected was covered first of all with a sticky aliva or urine and then fitted carefully into place by the skilful massons.
It was a laborious business and carried out with great care, for these homes must also be able to withsta,nd the strain of constant removal. Wherever it went, the caddis carried its home with it. Some of the grubs ate hugely of the calcareous deposits on the stones ; others found growths on piece of wood and weeds more to their liking ; othet preyed on the young flies.
Not all the caddis were massons, however. Some were rather clumsy carpenters, picking up tiny scraps of bark or leaves, or cutting off pieces of reeds and sticking them together to form a home. Theses fellows depended on camouflage rather than on producing something which would resist attack. One other caddis neither toiled nor spun ; it was lazy and timorous and depended chiefly on its own retiring nature to keep it out of danger.
In his wanderings and excursions, Far had come along way from his home redd but since he had found that excellent home in the shade of the ranunculus he had not bothered to travel farther.