Francis Francis, A Book on Angling. Being a complete tratise of the art of Angling in every branch, Philadelphie, J.B. Lippincott Company, 1920.

This little insect, which is the larva of various water-flies, is found at the bottom of streams. Its body being soft and easily damaged, nature has prompte dit to make a defense in the shape of a case which it provides for itself. This case is smooth in the inside, and is composed on the outside of minute ticks, or bits of gravel and other matters, and upon any alarm it retires within it. It is about the size of, and ather resembles in apppearance, a gentle ; it is, however, much more tender, and requires delicate handling in baiting.