CADDIS-FLIES 259 



of pupae of both of these types. The wings are folded 



up, the legs and antennae 

 Pupa. against the body, but not en- 



veloped in the same skin as 

 with the chrysalis of the butterfly or moth, and there is 

 a beak-shaped projection at the mouth. This beak- 

 shaped projection is, in fact, a pair of powerful jaws 

 or mandibleSj and its function is to force or tear open 

 the grating at the fore end of the movable case or to 

 break away the stones from the entrance of the fixed 

 case. The legs are furnished with heavy fringes, 

 which act as paddles when subsequently the pupa 

 requires to swim to the surface of the water. The 

 pupa, enveloped in a thin skin, crawls out of the case, 

 swims up through the water on its back, and finds a 

 convenient and dry place on stones or weeds, where it 

 makes its last change to the winged insect or imago. 

 The time elapsing between the emergence of the 

 imago and the swimming to the surface of the pupa is 

 probably in some species considerably longer than in 

 the corresponding change in the Ephemeridae. Bred 

 in captivity, the imago frequently occupied some hours 

 in breaking through the pupal skin after having 

 emerged from the caddis case. 



The imago immediately after the metamorphosis is 



pale in colour and generally 



Imago. soft in consistency, but rapidly 



assumes its full colouration. 

 It can fly fairly well, but remains generally hidden 

 in the grass or among the sedges in daylight, emerg- 



