INSECTS 



Md 



perhaps would migrate to some other part of the country; 

 here they would have children of their own, and the new 

 fourth generation would be unlike any of the three pre- 

 ceding; this generation would then produce another, 

 again different; and the latter would return to the home 



town of their grandparents 

 and great-grandparents, and 

 here bring forth children that 

 would grow up in the like- 

 ness of their great-great- 

 great-grandparents! This 

 seems like a fantastic tale of 

 fiction, too preposterous to 

 be taken seriously, but it is a 

 commonplace fact among the 

 aphids, and the actual gen- 

 ealogy may be even more 

 complicated than that above 

 outlined. Moreover, the 

 story is not yet complete, 

 for it must be added that all 

 the generations of the aphids, 

 except one in each series, are 

 composed entirely of females 

 capable in themselves of re- 

 production. In warm " cli- 

 mates, it appears, the female 

 succession may be uninter- 

 rupted. 

 How insects do upset our generalizations and our peace 

 of mind! We have heard of feminist reformers who would 

 abolish men. With patient scorn we have listened to their 

 predictions of a millenium where males will be unknown 

 and unneeded — and here the insects show us not only that 

 the thing is possible but that it is practicable, at least for 

 a certain length of time, and that the time can be in- 

 definitely extended under favorable conditions. 



[156] 



Fig. go. Cross-section through 



the base of the beak of an aphis. 



(From Davidson) 



The outer sheath of the beak is the 

 labium (Li/)> covered basally by 

 the labrum {Lm). The four in- 

 closed bristles are the mandibles 

 {Md) and the maxillae (Mx) i the 

 latter containing between them a 

 food canal {a) and a salivary canal 

 (b). Only the inner walls of the 

 labrum and labium are shown in 

 the section 



