ADAPTATIONS TO HAUNTS AND SEASONS 263 



interest to the student of insect biology, that it seems 

 advisable to devote, at this stage, a special chapter to the 

 subject, with illustrations of some of the ways in which 

 insects of different groups, in varying stages of their develop- 

 ment are found to be definitely fitted for certain haunts or 

 places of abode, and are enabled to survive the seasonal 

 changes of the year. 



We may well begin by considering the haunts of insects 

 from a wide viewpoint — that of the geographer. A com- 

 parative study of the distribution of various kinds and 

 groups of insects over the surface of the earth shows that 

 while very many are adapted by special modifications of 

 form and habit to a special and restricted environment, 

 others seem capable of adapting themselves to the most 

 diverse conditions so that they range widely over vast areas. 



The '' Painted Lady " Butterfly (Pyrameis cardui), for 

 example, may be found in the most widely separated regions. 

 In many seasons it is abundant in our islands, the large 

 butterflies with their handsome russet, black and white 

 wings flitting along lowland hedgerows or swooping in 

 bold flight over the bare tops of North British and Irish 

 hills. Swarms of the insects migrate northwards in May 

 and June from the Mediterranean district ; these lay their 

 eggs on thistles and other plants and the spring caterpillars 

 feed through the summer, transforming in August and 

 September into a second generation of butterflies. These, 

 however, cannot survive the winter in the climate of northern 

 and north-western Europe ; thus the butterfly, though its 

 powerful flight and the variety and wide range of the plants 

 on which its larvae feed, enable it every summer to invade 

 thousands of square miles of northern territory and there 

 produce progeny, can never establish itself as a true resident 

 outside those warmer regions, the conditions of which allow 

 it to carry on a succession of three or four life-cycles each 

 year. The species ranges eastward far across Asia into 

 India and Japan, and is found also abundantly in many parts 

 of America. It is therefore abundant, dominant, endued 

 with great power for wide dispersal, but limited in its 



