xix INSECT A: RHYNCOTA 289 



are described by Buckton as "spring cables." l The antennae of 

 Chermes are short compared with those of an Aphis. These 

 hibernating forms on the spruce are all female insects. In 

 the spring they awake to activity, and begin to pierce the 

 young growing tissues at the base of the bud and suck 

 nourishment from them. These punctures cause the formation 

 of such a gall as shown in Fig. 214, g\ the tissues swell up 

 and form a little green structure which is at first rather like 

 a young cone with scales arranged regularly on it and with 

 little cavities lying below the scales. 



Generation ^ s soon as tne ^ nsect responsible for this 



II. gall has fed sufficiently on the juices of the bud, 



Still on s he lays parthenogenetically a little cluster of 



pruce. stalked eggs, and then dies. The larvae which 



hatch from these eggs make their way into the cavities of the 



gall, and remain there feeding on its tissue, gradually acquiring 



their adult winged condition. In August, usually, the perfect 



insects creep out of the gall, which is now brown and woody, 



and the scales of which have separated, exposing the cavities 



(Fig. 214, g). The winged forms which come out are all females, 



and they now take one of the two following courses of action : 



Generation (^) Some ^ them stay on the spruce and lay 



III. parthenogenetic eggs which form fresh hibernating 

 On Spruce females of Chermes abietis ; 



(2) Some migrate to the larch and there lay 

 clusters of stalked eggs (Fig. 216, A and E\ which give rise to 

 female insects that hibernate on the larch, and are known 

 as Chermes lands (Fig. 216, C). 



Chermes This hibernating female awakes in March, and 

 laricis. j a y g parthenogenetic eggs on the larch twig, which 



IV. ^7 May have developed into both wingless and 

 On Larch, winged female forms. 



Generation The winged forms return to the spruce and lay 

 V. v and cj . parthenogenetic eggs there in the summer, and 

 On Spruce, these produce both female and male insects the 

 first appearance of males in the life-history. 

 Generation Finally, each of these females lays one fertilised 

 VI. or I. egg on the spruce in the autumn, which may 

 On Spruce, develop into such a hibernating female as was 

 described as Generation I. 



1 Monograph on British Aphides, by Buckton, vol. iv. , Ray Society. 

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