596 



it has been found only in Russia. The var. tardus occurs in Rassia 

 and Western Europe. 



Chermes viridanus, Choi., was found by the author in 1895 in Estland 

 (Russia), and later in Switzerland and other European countries. 

 It lives only on larches, without migrating to any other kind of tree. 

 Its life-cycle is incompletely known, the origin of the spring larvae 

 not having been directly traced ; they are found on young shoots of 

 larch trees after May. They give rise to winged forms, which do not 

 appear in North Russia before the end of June. They deposit eggs 

 on larch needles, which produce wintering larvae in two or three weeks, 

 the further development being unknown. As shown by Bdrner, they 

 are not identical with the spring larvae, and probably they hibernate 

 in the cracks of the bark, moulting in spring and becoming wingless 

 oviparous forms, corresponding to the stem-mothers from the eggs of 

 which the spring larvae hatch. If this is the case, the cycle of this 

 species is a two- yearly one. 



Small larvae of Chermes viridulus, Choi., were found by the 

 author in 1910 underneath the scales of the bark of Larix sibiriea in 

 Estland. Wingless, oviparous forms were found at the same time 

 which perished in the first half of July, while the larvae remained 

 sucking the bark till the first half of September. It is thought that 

 they hibernate and that next spring they produce wingless oviparous 

 forms, this species having thus only wingless stages. They were at 

 first thought to be the unknown stem-mothers of C viridanus, but 

 they differed from the wintering larvae of the latter both morpho- 

 logically and biologically. 



Chermes 'pectinatae, Choi., was first discovered by the author in 

 1887 near Petrograd and has hitherto only been found in Russia. 

 The author's species, C coccineus, is now considered a synonym of 

 this. The hibernating larval stem-mother of this species oviposits 

 on the fir bud, after having moulted three times ; the galls of this 

 species always cause a deformation of the whole bud and never have, 

 at their tip, a continuation of the shoot. The nymphs from the galls 

 transform into winged forms, which migrate to various species of 

 silver fir, such as Abies sibiriea, A. balsamea, etc., where they deposit 

 on the lower side of the needles a large heap of reddish yellow eggs ; 

 from these the wintering larvae of the false stem-mothers arise, and 

 these, having hibernated and moulted three times, lay dark yellow 

 eggs, from which dark grey larvae hatch in two or three weeks and 

 pass on to the young needles of silver fir. The larvae live on the 

 needles, moult four times, according to Marchal, and divide into two 

 varieties. Some, which are of a reddish violet colour, are only slightly 

 covered w^ith a white efflorescence, without waxy hairs, and become 

 nymphs with rudimentary wings. The others, which are of a dark 

 violet colour, with six lines of thick bundles of white hairs, become 

 wingless oviparous exules. The nymphs, having moulted, again give 

 rise to sexuparae, which appear in North Russia about the middle of 

 June, and migrate to firs, where they oviposit on the needles of young 

 shoots ; in two or three weeks the larvae of the sexuales hatch and 

 become, in about a month, adult males and females ; after pairing, 

 the females produce one egg, from which the larval stem-mother 

 appears in the second half of August and hibernates on the buds of 

 firs. The exules multiply on the needles in the same way as those of 



