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



at a pretty good conclusion with regard to them, I have thought 

 it the less advisable to keep back my observations, as they not 

 only furnish us with a new and interesting contribution to 

 the knowledge of Parthenogenesis, but also throw some light 

 upon many other long-known peculiarities in the reproduction 

 of insects. 



But, before I commence with the special exposition of my 

 investigations, a few words on the mode of life of the animals 

 may not be out of place, so far as this may be ascertained by 

 mere external observation, especially as it is fully described 

 from actual observation in the works of De Geer (Memoires, 

 tome iii. pp. 66-84, tab. 8), Kaltenbach (Monographic der 

 Familien der Pflanzenlause, 1843, pp. 193-206), and Ratzeburg 

 (Forstinsekten, 1847, Theil iii. pp. 195-205, tab. 12, 13)*. 



We treat in the first place of the common Fir-louse (C Abie- 

 tis, Linn.), which is divided into two species by both the last- 

 mentioned authors, namely C. Abietis, Kalt.= C. viridis,^Sitzeh., 

 and C strobilobiuSj Kalt.= C coccineus, Ratzeb. The distinction 

 of these two species, which, however, may be justified by the 

 size and position of their galls, is of no consequence to us ; for 

 both forms, which are very nearly allied even externally, agree 

 so closely biologically and anatomically, that 1 have looked in 

 vain for a distinction between them. (I will not, however, omit 

 to mention, in passing, that my investigations were made prin- 

 cipally upon the first of these two species or varieties.) 



By the investigations of the above-mentioned entomologists 

 it is satisfactorily established that the Fir-louse passes the win- 

 ter in the wingless state, in the form of a plump insect not 

 larger than a grain of sand, beneath the protective covering of a 

 whitish woolly coat, at the base of the scaly young buds of the 

 Fir. It is only in the following spring (April) that the little 

 animal begins to grow. It is then always found in its old 

 place, immoveable; and on closer examination its rostrum is ob- 

 served to be inserted deeply into the axis of the awakening bud. 

 That our insect pierces the individual leaves, as asserted by 

 Kaltenbach and also by De Geer, is incorrect; I have never 

 seen it elsewhere than in the above situation, and might even 

 suppose that it remains in this position until its death, without 

 ever changing the place of insertion of its rostrum to any extent. 

 Close above the perforation, even at this time, before the evolu- 

 tion of the buds, the axis of the young shoot, with the leaves 

 attached to it, begins to swell ; thus commences the first founda- 



* Hartig's memoir (Germar's Zeitschrift fiir die Entoraol. iii. p. 366) is 

 not in my possession at the moment ; and I pass it over with the less 

 reluctance, as his statements are frequently inaccurate and erroneous, — at 

 least as regards C. Abietis. 



