ADAPTATIONS TO HAUNTS AND SEASONS 299 



eggy early or late larva, pupa, or imago — adopted as the 

 winter form of the species. K. G. Blair, in a suggestive 

 discussion (1921) on the subject, points out that the egg and 

 pupa, both passive, might seem the most suitable stages 

 for the cold season when the food of many insects is scarce 

 or unobtainable ; yet '* these stages are in reality periods of 

 histological activity," for the embryo may then be formed 

 in the egg-shell and the imago reconstructed beneath the 

 pupal cuticle. It is not therefore surprising " that many 

 insects have adopted one of the physically more active, 

 though physiologically comparatively quiescent, stages, the 

 larva or the imago, as that in which to pass the winter." 

 While the life-cycle of many insects is rigidly adapted to 

 seasonal change, as it lasts just twelve months, and the 

 creature reaches the same stage of growth at the same time 

 every year, in many others there are two or more life- cycles 

 in the year, or the rate of development is retarded so that 

 several years are necessary for the appearance of a new 

 generation. Thus it may come to pass that the wintering 

 stage of the life-history is not found only in the winter, or 

 that during the cold season different members of the same 

 species may survive in different stages of growth. 



In previous chapters examples have been given of 

 insects of different orders that pass the winter in the adult 

 stage. Such are the large bright-hued vanessid butterflies, 

 like Aglais urticae (the *' Small Tortoiseshell ") or Vanessa io 

 (the *' Peacock "), also queen-wasps and bumble-bees, and 

 a large variety of beetles of different families. Among the 

 last-named, some ground-beetles (Carabidae) and rove- 

 beetles (Staphylinidae) are at least intermittently active, 

 pursuing and devouring smaller insects that may be available 

 as winter prey ; but click-beetles (Elateridae) and many 

 small jumping leaf-beetles (Chrysomelidae) such as the 

 notorious ** turnip-fly," remain quiescent under stones or 

 clods of earth. Wasps and bumble-bees are passive 

 throughout the winter and afford examples of true hiberna- 

 tion, " a torpid condition," as Blair remarks, " during which 

 no food is taken, no energy expended in movement, and 



