No. l6.] INSECTS OF CONNECTICUT. 35 



Rear wings as large as fore wings; posterior end of 

 abdomen lacking many-jointed filaments. . . .ODONATA 



8. Tarsi with less than five joints; labium cleft in middle 9 

 Tarsi with five joints ; labium entire 12 



9. Rear wings not broader than fore wings, sometimes 



absent, not folded in repose ; prothorax small, collar- 

 like 10 



Rear wings broader than fore wings ; both pairs present, 

 folded in repose; prothorax large, nearly flat on 

 dorsal surface PLECOPTERA 



10. Tarsi with less than four joints II 



Tarsi with four joints; wings, when present, equal in 



size ISOPTERA 



11. Tarsi with one or two joints ; always wingless 



MALLOPHAGA 



Tarsi usually three- jointed, occasionally two-jointed, in 

 which case wings are present ; fore wings larger than 

 rear wings CORRODENTIA 



12. Wings naked or slightly hairy 13 



Wings thickly covered with hairs TRICHOPTERA 



13. Mouth -parts not prolonged into a distinct beak, at most 



slightly conical NEUROPTERA 



Mouth-parts prolonged into a distinct beak MECOPTERA 



14. Prothorax free, body and wings not densely clothed 



with scales 15 



Prothorax not free ; maxillary palpi present, sometimes 

 rudimentary and obscure, in which case body and 

 wings are densely clothed with scales; tarsi usually 

 with claws, and never bladder-shaped 16 



15. Tarsi bladder-shaped, without claws ; wings four (some- 



times absent), narrow, fringed with long hairs 



THYSANOPTERA 



Tarsi not bladder-shaped, usually with claws ; wings not 

 fringed with long hairs ; maxillae bristle-like, without 

 palpi HEMIPTERA 



16. Mandibles often rudimentary, and bristle-like when 



present 17 



Mandibles well developed, fitted for biting; wings four . 

 (sometimes two or none), naked or with scattered 

 hairs. . .HYMENOPTERA 



