597 



C. strobilobius, the larvae from their eggs having a structure of the skin 

 similar to that of the larval false stem-mother. Thus the cycle of 

 this species is similar to that of C*. strohilobixs, though the intermediate 

 plant is not the larch, but the silver fir, and it is probable that some of 

 the eggs of the false stem-mothers produce larvae, which remain over 

 the winter, although the author has not been able to observe them. 



Chermes funitectus, Dreyfus, was first found in 1888 in Germany on 

 Tsuga canadensis and the author gives P. Marchal's description of it 

 (Contribution a I'etude de la biologic des Chermes, Annalesdes Sciences 

 Naturelles, 9 serie, Zoologie, vol. 18, 1913) [see also this Revieiv, Ser. A, 

 vol. iii, p. 344]. 



Chermes piceae, Ratz., is found in Western Europe on the bark 

 of trunks and branches of Abies pectinata ; it is not found in Russia, this 

 species of silver fir growing only in Poland. According to Marchal, 

 it has no migrations, multiplies parthenogenetically and lives only on 

 Abies pectinata (European silver fir). In 1901, Prof. E. Bouvier sent 

 to the author examples of peculiarly injured Abies 7iobilis var. glauca 

 (American silver fir) from the neighbourhood of Paris. This injury 

 appears to have been due to the presence of C. piceae var. bouvieri, 

 Choi., which differs from the typical form in not sucking directly on 

 the bark, but forms galls on it and on the young shoots. 



Chermes sihiricus, Choi., was discovered by the author in 1889 

 near Petrograd and has since been found in Switzerland. The wintering 

 larval stem-mother usually occurs at the base of the needle of fir trees, 

 near the bud at the end of the branches or on the bark of a shoot of 

 the previous year, not far from the bud. Owing to the fact that they 

 do not suck the bud itself, but the bark at some distance from it, 

 their influence on the formation of the shoots differs from that of other 

 species of Chermes. The shoot is usually shortened and thickened 

 and the thickened bases of the needles on one side of it grow together. 

 The larvae appear in the first half of June as nymphs, with rudimentary 

 wings ; the galls usually open earlier than those of any other Chermes. 

 The nymphs moult and become winged and fly from the fir trees to 

 Plnus cembra (Siberian cedar) on the needles of which they oviposit. 

 The larval false stem-mothers appear in two or three weeks, pass on 

 to the bark of cedars and remain there over the Avinter ; next spring 

 they moult and appear as wingless forms of varying colour. They 

 deposit yellow eggs, giving rise to individuals which pass on to the 

 green bark of the young shoots and split into exules and nymphs, 

 which become sexuparae after moulting. The exules continue to 

 develop on the bark of cedars, while the sexuparae return to firs and 

 oviposit on them, producing sexuales. The females deposit one egg 

 each, which produces the wintering larval stem-mother. Thus the 

 life-cycle of C sibiricus resembles that of C. strobiloljiiis, but for the 

 intermediate plant, which is not larch but cedar. 



Chermes pini, Koch, and C. orientalis, Dreyfus, constitute one species, 

 divided into two biological varieties, a northern one, C. pini var. 

 pinicola, which has only a rudimentary migration to firs, multiplies 

 almost exclusively by parthenogenesis and very rarely produces galls, 

 though it gives rise to a large number of winged exules ; and a southern 

 one. Ch. jyini var. orientalis, Dreyfus, which has a complete cycle, 

 forming galls on Caucasian firs {Picea orientalis), not on European fir 

 {Picea excelsa), and producing, on pines only, a small number of winged 

 exules. 



