9 months. At the beginning smaller aggregations are scattered over the hibern- 

 ation area; in warm days with intensive insolation, fly the coccinellids over 

 the hibernation quarter and gradually concentrate into a smaller number 

 of great aggregations, in the same places year after year. The upper individuals 

 continuaUy creep over also in warmer winter days. In spring before the emer- 

 gence the copulation takes place in the hibernation quarters. 



In females the imaginai diapause is connected with gonotrophic dissociation: 

 their Ovaria fail to mature because all the nutritive materials are used to form 

 reserve. Therefore, during the whole hibernation, even by emergence, the im- 

 mature Ovaria are submerged in the large fat body together mth the ovarioles 

 richly supphed by tracheae. As the gonade maturation of males is less exigent 

 of energy the spermiogenesis takes place soon after emergence. Only close 

 before the hibernation the males stop the activity of testicular folioles 

 containing already encysted spermatozoits. The seminal vesicles, too, are 

 filled with free Uving spermatozoits during the whole hibernation. Towards 

 the end of the hibernation period, one or three weeks before emergence, the 

 activity of testicular f olicles is renewed; the males start copulation and fertilize 

 immature females by spermatozoits stored during the winter, so that all 

 the females emerge with a spermatozoit reserve in their spermathecae. This 

 different sexual activity in the final period of liibernation is the source of 

 sexual differences in amounts of reserve materials. 



Imagoes of both sexes hibernate with their alimentary canal empty and 

 with large reserves of fats and glycogen in their fat bodies. During the hi- 

 bernation the fat and glycid reserves are consumed very slowly owing to 

 the low metaboUsm rate. Only shortly before the emergence (1 — 2 weeks) a 

 more significant reduction of fat reserves can be observed, especially in 

 males. On the other hand the females show a considerable increase of glycogen 

 contents in this period. In males, having the glycogen amount rather hig- 

 her than females during the whole hibernation, the glycogen level rises later 

 reaching only a haK of the increase of females. 



The oxygen consumption varied about the value 750 ml/g/hour during 

 the whole hibernation. Even when the fat and glycogen contents changed 

 no remarkable alterations in oxygen consumption were observed. 



The great frost resistence during the hibernation disappears in the final 

 period before the emergence. 



During the liibernation the imagoes of both sexes could be induced to 

 resume their movement (quick crawling and flight), mating, feeding and 

 defecation. But it could be observed that owing to this the fat and glycogen 

 reserves were rapidly consumed and the imagoes perished, the death being 

 more rapid in active mature males whose fat body contains relatively less 

 fat-protein grains. These results, however, could be influenced by an unspecific 

 nutrition, the aphid Pergandeida medicaginis Koch. Although this aphid 



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