The _Phryganidæ_, or Caddis Flies, are known by their larvæ, of which anglers make great use. Réaumur classed them as aquatic moths. The soft and delicate body of the larvæ is protected by a case, to which they cling by two hooks, placed at the extremity of their abdomen. They are called by different names in allusion to their habits; as, for instance, case worms, from their living in a case covered with little bits of wood or sand, which they draw after them as they go. Their scientific name, _Phryganea_, signifies _fagot_.[120] The _Phryganeæ_, in the adult state, very much resemble moths. They approach them in having rudimentary mouths, and wings without articulations, but furnished with small hairs, analogous to the scales of Lepidoptera. They may be said to form a sort of connection between the Lepidoptera and Neuroptera. They have been called _Mouches papilionacées_, or Papilionaceous Flies. The eggs laid by the female _Phryganea_ are enclosed in gelatinous capsules, which swell in the water and attach themselves to stones, &c. The larva has the appearance of a little worm without feet. It is soon hatched, and resembles at first a little black line, and may be easily reared in an aquarium. The operation of making the silky case which it draws after it, and which protects its abdomen, may then be observed. When it is disturbed, it retreats entirely within its case. The interior is smooth, and lined with mud; on the exterior it is fortified with stones, &c. [120] From [Greek: phryganion], a stick. [Illustration: Fig. 418. Regular cases of a Phryganea.]