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at the base of the buds, especially of the leading shoots. The stem- 

 mother moults three times, after which it becomes mature and acquires 

 an ovipositor, its full development lasting about a month. Near 

 Petrogi'ad, they are mature at the beginning of June. During 

 oviposition, the stem-mother continues to suck the bud of the fir, 

 producing an irritation, which deforms it and delays its growth. 

 Before the last egg is laid, the first have already hatched and the 

 resulting larvae creep between the scales and also suck the bud, thus 

 furthering the production of the gall. About the middle of summer, 

 the gall reaches the size of a hazel nut, or even of a walnut, its size 

 depending upon the number of stem-mothers, which have contributed 

 to its foilnation. Frequently the whole shoot is transformed into a 

 gall, but in the majority of cases, the deformation affects only the 

 base of the bud, so that a more or less lengthy shoot of normal structure 

 emerges from the end of the gall. The larvae live during the summer 

 inside the gall and moult three times. About the middle of summer 

 (usually in the second half of July near Petrograd), the galls ripen 

 and gi'adually burst open. At this time, the larvae, which have already 

 passed into the nymphal stage, leave the gall, and moulting again 

 on the same or the next day, become winged individuals. These 

 soon leave the tree on which they have bred and settle on the needles 

 of any larch trees in the neighbourhood, and deposit on them large 

 heaps of dark green eggs. In two or three weeks, green larvae hatch 

 from these eggs and remain over the winter in cracks, etc., of the bark. 

 These winged individuals are called migrantes alatae, the larvae 

 produced by them being called false stem-mothers (fundatrices spuriae) 

 as distinguished from the real stem- mothers (fundatrices verae) which 

 live on firs and produce the galls. The false stem-mothers become 

 active in spring and attack the young buds of the larches. After 

 moulting three times, they deposit a small heap of bright green eggs, 

 from which larvae of a dirty green colour hatch in about two weeks. 

 These give rise to the winged forms which were previously regarded 

 as a separate species, Chermes lands, Hartig. Near Petrograd, these 

 appear on larches in the first half of June ; they are called sexuparae, 

 because, migrating back to fir trees, they deposit the eggs which 

 produce a new sexual generation of both males and females (sexuales). 

 Each sexupara lays about 10 greenish yellow eggs, mostly on old needles 

 on the lower side of the branches ; the sexuales hatch in about two 

 weeks; after pairing, the males die, while the females penetrate 

 underneath the scales of the bark, mostly near young shoots and each 

 deposits one yellow egg. From this egg, the larva of the stem-mother, 

 described above, hatches in August and September. Thus the whole 

 cycle of this species lasts two years and contains five generations. 

 As Dreyfus pointed out in 1889, the spring generation breeding on 

 larches has two varieties, a green and a yellow one, and the recent 

 •observations of the author in Russia and Switzerland confirm 

 the fact that some of the winged forms migrating to larches deposit 

 on them yellowish green eggs, instead of dark greei\ ones, which 

 gradually become dark green in one or two weeks. The galls from 

 which such winged forms arise, usually open later than those which 

 produce the forms depositing dark green eggs, the process being 

 delayed till the first half of August. The author proposes to call the 

 green generation var. virldsscens and the yellow one var. lutescem. 

 A diagram of the life-cycle of this species is given. 

 (C208) a 



