174 HONEY-DEW 



thetical connection, the name of honey-dew would indeed 

 be a peculiarly appropriate one. I may mention in passing 

 that tobacco is quite fatal to almost all insects, a fact which 

 I present gratuitously to the blowers of counterblasts, who 

 are at liberty to make whatever use they choose of it. 

 Quassia and aloes are also well-known preventives of fly or 

 blight in gardens. 



The most complete life-history yet given of any member 

 of the aphis family is that which M. Jules Lichtenstein 

 has worked 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 

 larvae so produced themselves once more give origin to 

 more larvas, 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 larvae 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 gene- 

 rations 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 gene- 

 rations. 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 found- 

 resses were first hatched out, all the intervening generations 



