162 HONEY-DEW 



The life-history of the rose-aphis, small and familiar 

 a is the insect itself, forms one of the most marvellous 

 and extraordinary chapters in all the fairy tales of modern 

 science. Nobody need wonder why the blight attacks his 

 roses so persistently when once he has learnt the unusual 

 provision for exceptional fertility in the reproduction of 

 these insect plagues. The whole story is too long to give 

 at full length, but here is a brief recapitulation of a year's 

 generations of common aphides. 



In the spring, the eggs of last year's crop, which have 

 been laid by the mothers in nooks and crannies out of reach 

 of the frost, are quickened into life by the first return of 

 warm weather, and hatch out their brood of insects. All 

 this brood consists of imperfect females, without a single 

 male among them ; and they all fasten at once upon the young 

 buds of their native bush, where they pass a sluggish and 

 uneventful existence in sucking up the juice from the veins 

 on the one hand, and secreting honey-dew upon the other. 

 Pour times they moult their skins, these moults being in 

 some respects analogous to the metamorphosis of the cater- 

 pillar into chrysalis and butterfly. After the fourth moult, 

 the young aphides attain maturity ; and then they give 

 origin, parthenogenetically, to a second brood, also of im- 

 perfect females, all produced without any fathers. This 

 second brood brings forth in like manner a third generation, 

 asexual, as before ; and the same process is repeated with- 

 out intermission as long as the warm weather lasts. In 

 each case, the young simply bud out from the ovaries of 

 the mothers, exactly as new crops of leaves bud out from 

 the rose-branch on which they grow. Eleven generations 

 have thus been observed to follow one another rapidly in 

 a single summer ; and indeed, by keeping the aphides in a 

 warm room, one may even make them continue their re- 

 production in this purely vegetative fashion for as many as 



