INSECTS 



385 



increasing in size, and developing some of the adult characteristics. 

 The fully-formed nymph ultimately creeps up the stem of some 

 plant till it is out of the water, and then remains motionless. The 



*-h ' '*- w T^ '" ft ..11,1 m.jn 1 



Fig 905. — Caddis-Moth {Phryganea striata) and its Larva 



skin ot the back now splits, and the perfect insect makes its way 

 out of the enclosing skin, its wings being at first flabby and 

 shrivelled. They soon expand and assume their proper form, 

 and the dragon-fly then takes wing, commencing 

 a life in the air which is quite as predaceous as 

 the life which its nymph led in the water. The 

 amount of metamorphosis is not nearly so consider- 

 able as in some of the other insects to be described, 

 and, as a matter of fact, the order of Net-winged 

 Insects includes so many dif- 

 ferent kinds of life -history, 

 that it really comes under the 

 last heading as well as under 

 this. But it is thought best 

 to keep them together, so as 

 to prevent confusion. 



Caddis-Flies (Phryganeidce) 

 are net-winged insects which 

 pass through a complete meta- 

 morphosis, hatching out as 

 larvae, which construct cases 

 for themselves (see vol. ii, 

 p. Zil\ ^rid as "caddis-worms" are well-known inhabitants of 

 fresh water. After a time the larva passes into a motionless pupa 



Fig. go6. — Larva and Pupa of a Caddls-Moth {Oxyethira 

 costalis). A, Larva and its case, x 17. B, Pupa in its in- 

 vestment, with four anchoring pads, X 16. 



