vm] THE LIFE-STORY AND THE SEASONS 95 



their underground chambers, then climb up the tree 

 and lay on the shoots eggs, from which will be hatched 

 the grubs destined to grow within the oak-apples 

 into the summer sexual brood of flies. 



The Lepidoptera afford examples of hibernation 

 in all stages of the life-history. In this order a few 

 large moths with wood-boring caterpillars, the 'Goat' 

 (Cossus) for example, undergo a development extend- 

 ing over several years, while at the other extreme 

 a few small species may have three or more complete 

 cycles within the twelve months. But in the vast 

 majority of Lepidoptera we find either one or two 

 generations, definitely seasonal, within the year ; 

 the insect is either ' single-brooded ' or ' double- 

 brooded/ 



Almost every winter one or more letters may be 

 read in some newspaper recording the writer's sur- 

 prise at seeing on a sunny day during the cold 

 season, one of our common gaily-coloured butterflies 

 of the Vanessa group, a ' Tortoiseshell ' or ' Red Ad- 

 miral,' flitting about. Surprise might be greater did 

 the observers realise that the imaginal is the normal 

 hibernating stage for these species. Emerging from 

 the pupa in late summer or autumn, they shelter 

 during winter in hollow trees, under thatched eaves, 

 in outbuildings or in similar situations, coming out 

 in spring to lay their eggs on the leaves of their 

 caterpillars' food-plants. The larvae feed and grow 



