452 SYNOPTIC COLLECTION. 



drags its case about with it by means of its legs and some- 

 times its mandibles, these parts are well developed. The 

 case is large enough for the respiratory filaments on each 

 side of the abdomen (fig. i) to move freely in the water. 

 In fact, the larva is able to turn itself in its case so that 

 its head appears indiscriminately at either end. 1 The 

 larva is exceptional in having no antennae and at the 

 same time small eyes, for when the former organs are 

 absent the eyes are usually well developed. 



When the larva is ready to become a pupa (fig. 3), it 

 closes both ends of its tube with silk spun from the spin- 

 neret which is near the mouth, as in Lepidopterous cater- 

 pillars. During the pupal stage the antennae develop, 

 the mouth parts become reduced in size, though the 

 mandibles still persist, and the respiratory filaments disap- 

 pear. 



The appendages of the pupa are free as in all the 

 pupae so far described. 



The adult (PL 1147, fig. 4) has a small head, a collar- 

 like prothorax, a comparatively large mesothorax, and a 

 slender abdomen characters which we shall see are 

 shared by moths. The caddis-fly (No. 1148, Neuronia, 

 one of our largest species) also possesses hairy wings 

 (hence the name Trichoptera, meaning hair and wing), 

 which sometimes become scale-like. The two wings on 

 each side are fastened together so that they act as one 

 thereby increasing the power of flight. When at rest the 

 wings are held roof-like over the body. 



The mouth parts of the adult are transitional between 

 the biting and sucking type. The mandibles are obsolete, 

 and in some genera, according to Hagen, 2 the mouth 



1 McLachlan, Trans. Ent. Soc. London, (3), V, 1865, p. n. 



2 Quoted by Packard, Ent. for Beginners, 1889, p. 90. 



