INSECTS
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 preceding; this generation would then produce another, again different; and the latter would return to the home
Fig. 90. Cross-section through the base of the beak of an aphis.
(From Davidson)
The outer sheath of the beak is the labium (Lb), covered basally by the labrum (Lm). The four in-closed bristles are the mandibles (Md) and the maxillae (Mx), 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
town of their grandparents and great-grandparents, and here bring forth children that would grow up in the likeness 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 genealogy 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 reproduction. In warm climates, it appears, the female succession may be uninterrupted.
How insects do upset out 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 indefinitely extended under favorable conditions.
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