INSECTS AND THEIR NEAR RELATIVES 27 



G. Wings fringed with long hairs. Size 

 usually less than one-eighth inch in 

 length. Mouth-parts indeterminate in 

 type. Thrips. Physopoda. 

 GG. Wings without fringes. Very easily 

 broken off or shed by the insect. Ter- 

 mites. Isoptera. 

 FF. Wing veins more numerous. 



G. Finely netted wings. Neuroptera. 

 GG. Wings with fewer cross veins. Head 

 prolonged into a beak. Scorpion-flies, 

 etc. Mecoptera. 

 DD. Wings unequal in size. 



F. Wings entirely membranous. 



G. Front wings longer than the hind 

 wings. 



H. Wings finely netted. Abdomen 

 with long tail-like filaments. Eph- 

 emerida. 

 HH. Wings with fewer cross veins. 



I. Hind tarsi with two or three 

 segments. Psocids. Corrodentia. 

 II. Hind tarsi with four or five seg- 

 ments. Hymenoptera. 

 GG. Hind wings broader than front wings. 

 H. Wing veins with hair-like scales. 



Trichoptera. 

 HH. Wings without scales along veins. 



Hind wings folded. Plecoptera. 

 FF. Front wings leathery or hardened. 



G. Front wings leathery but flexible and 

 usually partially transparent. Orthoptera. 

 GG. Front wings hardened, seldom flexible. 

 Coleoptera. 



