Falling in Love, page 159 by Grant Allen
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d out with so much care in the case of the phylloxera of the oak-tree. In April, the winter eggs of this species, laid in the bark of an oak, each hatch out a wingless imperfect female, which M. Lichtenstein calls the foundress. After moulting four times, the foundress produces, by parthenogenesis, a number of false eggs, which it fastens to the leaf-stalks and under side of the foliage. These false eggs hatch out a larval form, wingless, but bigger than any of the subsequent generations; and the larvæ so produced themselves once more give origin to more larvæ, which acquire wings, and fly away from the oak on which they were born to another of a different species in the same neighbourhood. There these larvæ of the second crop once more lay false eggs, from which the third larval generation is developed. This brood is again wingless, and it proceeds at once to bud out several generations more, by internal gemmation, as long as the warm weather lasts. According to M. Lichtenstein, all previous observations have been made only on aphides of this third type; and he maintains that every species in the whole family really undergoes an analogous alternation of generations. At last, when the cold weather begins to set in, a fourth larval form appears, which soon obtains wings, and flies back to the same kind of oak on which the foundresses were first hatched out, all the intervening generations having passed their lives in sucking the juices of the other oak to which the second larval form migrated. The fourth type here produce perfect male and female insects, which are wingless, and have no sucking apparatus. The females, after being impregnated, lay a single egg each, which they hide in the bark, where it remains during the winter, till in spring it once more hatches out into a foundress, and the whole cycle begins over again. Whether all the aphides do or do not pass through corresponding stages is not yet quite certain. But Kentish farmers believe that the hop-fly migrates to hop-bines from plum-tr