Edward Cave, The Boy Scout’s Hike Boo: The First of a series of Handy Volume of Information and Inspiration, New York, Doubleday & Company, p. 185, 1913.

The « caddies » are found in their case, on the bottom of streams, on the gravel and on the sides of stones or under them. Trout eat them case and all, but it is best to pull the larva (grub) or pupa (worm) out and thread it on the hook.