17*2 Life-History of the Larch Chernies 



the sexual individuals, descriptions of which, indeed, seem to be entirely 

 lacking in the voluminous literature ^ on the structure and classification, 

 and in the majority of cases without anything like a complete knowledge 

 of the life-histories. 



The establishment of a new Genus for nearly every new species 

 which comes to hand can surely be but a hindrance rather than a help 

 to a sound systematic classification in the future. 



Two species of Chermes in Great Britain are known to inhabit 

 Spruce and Larch, respectively, as their host and intermediate host. 

 Both form galls on Spruce and migrate to Larch by means of a winged 

 parthenogenetic generation, and again return to Spruce by a similar 

 winged generation, which, however, is different in details of structure 

 and habit from the former. 



Both these insects have received much attention recently, and an 

 outstanding paper by Mr H. M. Steven, entitled "Contributions to the 

 knowledge of the family Chermesidae," has been published in the Fro- 

 ceedings of the Royal Society of Edinburgh, vol. xxxvii. Part III, No. 21, 

 June, 1917. 



This paper supplies much information upon the life-cycles of the 

 two Chermes mentioned, namely Chermes viridis, Ratz., and Cnaphalodes 

 strohilobius, Kalt., and also upon the species of Cholodkovsky, which are 

 confined to the Spruce only. It may be stated here that no discussion 

 is advisable as yet upon the probability of the latter two species being 

 identical with, and forming a phase of the life-history of, the two first- 

 named species. 



With regard to the nomenclature of the generations in the Cher- 

 mesidae, the terms applied to two only have been used constantly since 

 1878, namely the Fundatrix and the Sexuales. The term Sexupara has 

 been in general use since 1889, but the names given to the other winged, 

 and wingless generations which deposit their eggs on the intermediate 

 host-tree have undergone constant changes. 



Mr Steven has again revised the terms for the latter in his paper, and 

 the establishment of the names Gallicola migrans, and GaUicola non- 

 migrans for the winged forms emerging from Spruce galls, and Colonici 

 sistens and progrediens for the Larch generations, is admirable. 



In the present paper, it is proposed to give a detailed description of 

 the parthenogenetic cycles on the Larch, but for the sake of clarity, a 

 brief summary of Mr Steven's woik on the Spruce cycle is recalled. 



' Except in Paul Alarchal's paper, Annalvs dfs Sciences naliinlles (Zonlogie), 9th sericp, 

 vol. XVIII, 1913, where a few figures of fcJoxuales of the genus Pineus only are given. 



