Stone flics 



203 



The stonefiies (order Plecoptcra) are all aquatic. 

 They live in rapid streams, and on the wave-washed 

 rocky shores of lakes. They are among the most 

 generalized of winged insects. The adults are flat- 

 bodied inconspicuous creatures of secretive habits. 



Little is seen of 

 them by day, 

 and less by 

 night, except 

 when some bril- 

 liant light by the 

 waterside at- 

 tracts them to 

 flutter around it. 

 The colors are 

 obscure, being 

 predominantly 

 black, brown or 

 gray; but the 

 diurnally-.a cliy£- 

 foliage inhabit- 

 ing chlor o perlas 

 are pale green. 

 They take wing 

 awkwardly and 

 fly rather slowly, 

 and may often 

 be caught in the 

 unaided hand. 

 They are readily 

 picked up with 

 xhe fingers when at rest. The wings (sometimes 

 aborted) are folded flat upon the back. They are 

 rather irregularly traversed with heavy veins. The 

 tarsi are three- jointea'. This, together with the flat- 

 tened head, bare skin,' anc long forwardly-dr^cted 



Fig. 1 10. An adult stonefly , Perln immarginata. 



