326 M. Leuckart on the Reproduction of Bark- lice. 



Phylloxera, but I have scarcely any doubt that they would have 

 proved without exception to be female animals. From all ana- 

 logy, these winged individuals are the progeny of the wingless 

 forms observed by me, which, on their part, represent the first 

 generation of Chermes, and will have passed the winter either as 

 young animals, or, as their later appearance would almost lead 

 us to believe, as eggs. 



If the latter supposition be well founded, our Phylloxera 

 would be distinguished thereby not only from Chermes Abietis*, 

 but also from C. Laricis, which otherwise approaches it most 

 closely in form and mode of life (residence on the surface of the 

 leaves, and incapability of forming galls). 



With regard to the conditions of reproduction, however, the 

 same statements apply to the latter as to other species pre- 

 viously referred to. The Larch-louse also only exhibits the 

 female sex in both wingless and winged individuals ; it always 

 consists, as far as I am aware, only of parthenogenetic virgins. 



But with regard to the relation in which these two forms of 

 individuals stand to each other, I have not been able to arrive at 

 so clear a conclusion as in the case of C. Abietis. Nevertheless 

 it almost appears as if C. Laricis behaved somewhat differently 

 in this respect. According to the statements of Kaltenbach and 

 Ratzeburg, there is indeed no doubt that the minute creatures 

 which pass the winter on the still undeveloped buds are de- 

 veloped first of all only into wingless individuals ; but it is 

 equally certain that in this case the winged individuals make 

 their appearance very early, and occur for a long time together 

 with wingless females. I found such winged individuals as early 

 as the end of May, a few weeks after the first eggs, which in 

 this species are but few in number, were met with. Moreover, 

 according to Ratzeburg' s observations, the eggs of the first ge- 

 neration do not produce winged individuals exclusively, as in 

 C. Abietis, but wingless forms are produced at the same time ; 

 the latter, however, are somewhat different from the original 

 wingless animals, and produce a third generation in the same 

 year. That the winged individuals lay eggs, like the wingless 

 ones, was unknown to Ratzeburg; I have, however, convinced 

 myself of this in the most certain manner, but must remark that 

 the number of these eggs is less than that produced by the wing- 

 less females. 



By the greater number of the consecutive generations, and 

 also by the fact that these generations are represented, at least 

 in part, simultaneously by winged and wingless individuals, 



* It was by mistake that, in my memoir on the alternation of generations 

 and Parthenogenesis in insects, I stated that the eggs of C. Abietis passed 

 through the winter. 



