CLASSIFICATION OF INSECTS. 



79 



flies on account of the peculiar form of the caudal 

 part of the abdomen of the male (Fig. 67). This at 

 first sight suggests the corresponding part 

 of a scorpion, but in reality the two are 

 very different. 



Very closely allied to the scorpion-flies 

 are the insects of the genus Bittacus (Bif- 

 ta-cus). These insects have long narrow 

 wings, long legs, and a slender 

 abdomen. They resemble crane- 

 flies very closely when on the wing. In 

 this genus the caudal appendages of the 

 male are not enlarged as in Tanorpa. 



The species of the genus Boreus {Bo're- 

 us) are remarkable for occurring on snow in 



_ , the winter in our Northern States. In this 

 Fig. 67. 



Tail of a genus the females are wingless, while the 



scorpion- , , . 



fly. males have rudimentary wings. 



Flo. 66.— A 

 scorpion-fly. 



Order Trichoptera (Tri-chop'te-ra). 

 The Caddice-flies or Caddice-worms. 



The members of this order have four wings ; these 

 are membranous, furnished with numerous longitudinal 

 veins, but with only few cross-veins, and are more or less 

 densely clothed with fiairs. The mouth-parts are rudi- 

 mentary. The metamorphosis is complete. 



Fig. 68.— A caddice-fly. 



Fig. 69. — A caddice-worm. 



This order is composed of the caddice-flies and 

 caddice-worms (Figs. 68 and 69), which are discussed 



