INSECT ENEMIES. . 125 



three-jointed beaks, which puncture the tender foliage, 

 and through which they suck out the juices of plants. 

 Their eyes are round, without eyelets. Their antennae 

 are long and tapering. Their legs are long and slender. 

 There are but two joints to their feet. Their wings are 

 nearly triangular, and the upper wings, longer than the 

 body, are nearly twice as large as the lower. In repose 

 these wings cover the body like a steep roof. 



The most wonderful thing about them is the way they 

 multiply. The males die soon after they pair in autumn. 

 The females lay their eggs on the bark near the leaf buds, 

 and then die. In spring, when the leaves begin to grow, 

 the eggs hatch and they begin their depredations. All 



Fig. 113. THE GREEN APHIS. 



the young lice are wingless females. In ten or twelve 

 days they attain to maturity, and by a viviparous genera- 

 tion they begin to give birth to a daily increase of about 

 twenty. This second generation are also wingless fe- 

 males, and soon multiply by the same process as did the 

 first. Thus they multiply throughout the season, with- 

 out the appearance of a single male, till in autumn they 

 produce a brood of both sexes, as well as the viviparous 

 form already described. During the summer, some 

 of the females acquire wings, and, dispersing to other 

 trees, found new colonies. They are generally wingless, 

 but when winged, look like the males, with a black head, 

 thorax, and antennae, black dots in a row along each 



