CHAPTER III 



STONE-FLIES, BOOK-LICE, MAY-FLIES, AND 

 DRAGON-FLIES 



WE now come to the fourth order of insects, the 

 Plecoptera, which comprises the stone-flies. 1 

 They have biting mouth-parts, and two pairs of wings, 

 which are alike in texture, with a complex network of 

 veins, the hind-wings being much the larger. When 

 closed, all the wings lie flat upon the back, and over- 

 lap, so that only one fore-wing is seen ; while the front, 

 or costal, portion of each fore-wing is turned down- 

 wards, thus covering and protecting the sides of the 

 body. In many male stone-flies, however, the wings 

 are so much reduced that they are useless for flight. 

 The antennae are long, many jointed, and slender, and 

 there are usually two long cerci at the extremity of 

 the abdomen, so that the insect appears to have a pair 

 of antennae at each end. 



The manner of growth and development differs little 

 from that which we have already seen in the case of 

 the earwig or the cockroach. Except for the absence 

 of wings, the young stone-fly closely resembles its 

 parents in form ; but its surroundings are very 

 different, for it lives in rapidly flowing streams. 

 Although it is able to swim well with its legs, it 

 seldom employs this means of progress, preferring to 

 1 Perlida. 



