THE ORDERS OP itiSECTS. ig 



terminates in two long filaments. The larva is found under 

 stones in rivers. 



The Caddis Flies are sometimes formed into a separate Order, 

 called Trichoptera,) or Hairy-winged Insects. They are of 

 different sizes, up to about two inches across the wings. Phry- 

 ganea Grandis is the largest and one of the commonest species. 

 They much resemble brown moths with rather narrow wings, 

 which are clothed with hairs instead of scales, and their mouth 

 is very imperfectly developed. Their larvoe live in water, where 

 they form cases for themselves composed of bits of stick, stone, 

 small shells, or any other material suitable for the purpose, which 

 they can lay their hands on. They assume the pupa state in 

 these cases, sometimes forming a slight cocoon. 



Stone Fly (Perla Bicaudata), natural size. 



The Order Hymenoptera has four transparent wings, which 

 are generally small in comparison with the size of the body. The 

 fore and hind wings are linked together by a series of minute 

 hooks on the borders. The female is always provided with a 

 powerful ovipositor, which is frequently modified into a sting. 

 The principal groups included in this Order are the Saw Flies, 

 the Gall Flies, the Ichneumons, the Ruby-Tails, and the Ants, 

 Wasps, and Bees. 



The Saw Flies (Tenthredinidce} derive their name from the 

 boring apparatus of the female being modified into a pair of 

 saws, which are used to cut a crevice in the bark or leaves of 

 plants to receive the eggs. These eggs produce larvce resembling 

 those of Lepidoptera, but with from eighteen to twenty-two legs, 

 whereas Lepidopterous larvce never have more than sixteen. 

 The best known species is the Gooseberry Fly (Nematus 

 Ribesii}, a yellow, four-winged fly, more or less spotted with 



