Fleas. Flies. 127 



CHAPTER XXIV. 



INSECTS WHICH UNDERGO PERFECT METAMORPHOSES. 



THE four orders of insects which follow are small, 

 but contain some interesting forms which deserve a 

 passing notice. FlG ?2 



ORDER VI. Neuroptera, 

 nerve-winged insects, including 

 the scorpion-flies (fig. 7 2 ^snake- 

 flies, and ant-lions. These in 

 their perfect stage possess a 

 mouth fitted for chewing, and 

 four equal membranous wings, Pan n. or Scorpion-fly, 

 of which the hinder pair are never folded. Few of 

 these insects are natives of this country. 



ORDER VII. Trichoptera, including the caddis- 

 flies which have hair-clad or scaly unequal wings, the 

 hinder of which are folded. Their larvae agglutinate 

 small shells, stones, straws &c. by silken threads 

 secreted by a small spinning gland placed on the 

 lower lip, and of these they make cases in which they 

 live. Having attained its full size, the pupa fixes its 

 case under water and spins a silken network or grating 

 over each end of it, thus shutting itself in for its pupa 

 sleep, while it does not exclude the water which it 

 requires for breathing. After this stage of rest the 

 pupa by its strong jaws bites through its prison, and 

 after moulting assumes its adult form. 



ORDER VIII. Strepsiptera includes the curious 



