PLANT LICE 



surviving virgins give birth in forlorn hope to a brood 

 that must be destined for the end. But now, it appears, 

 another of those miraculous events that occur so fre- 

 quently in the lives of insects has happened here, for the 

 members of this new brood are seen at once to be quite 

 different creatures from their parents. When they grow 

 up, it develops that they constitute a sexual generation, 

 composed of females and males! (Plate 2 A, B.) 



Feminism is dethroned. The race is saved. The mar- 

 riage instinct now is dominant, and if marital relations 

 in this new generation are pretty loose, the time is Octo- 

 ber, and there is much to be accomplished before winter 

 comes. 



The sexual females differ from their virgin mothers 

 and grandmothers in being of darker green color and in 

 having a broadly pear-shaped body, widest near the end 

 (Plate 2 A). The males (B) are much smaller than the 

 females, their color is yellowish brown or brownish green, 

 and they have long spiderlike legs on which they actively 

 run about. Neither the males nor the females of the green 

 apple aphis have wings. Soon the females begin to pro- 

 duce, not active young, but eggs (D). The eggs are de- 

 posited most anywhere along the apple twigs, in crevices 

 where the bark is rough, and about the bases of the buds. 

 The newly-laid eggs are yellowish or greenish (D), but 

 they soon turn to green, then to dark green, and finally 

 become deep black (E). There are not many of them, 

 for each female lays only from one to a dozen; but it 

 is these eggs that are to remain on the trees through the 

 winter to produce the stem mothers of next spring, who 

 will start another cycle of aphid life repeating the his- 

 tory of that just closed. 



The production of sexual forms in the fall in temperate 

 climates seems to have some immediate connection with 

 the lowered temperature, for in the tropics, it is said, 

 the aphid succession continues indefinitely through par- 

 thenogenetic females, and in most tropical species sexual 



[167] 



