vm] THE LIFE-STORY AND THE SEASONS 93 



their transformations so rapidly that several succes- 

 sive broods appear in the spring and early summer, 

 with the larger click-beetles whose larvae, the equally 

 notorious ' wire worms,' feed on roots for three or 

 four years before they become fully grown. Among 

 the Diptera, the 'leather-jacket' grub of the crane-fly, 

 feeding like the wireworm on roots, has a larval life 

 extending through the greater part of a year, while 

 the maggot of the bluebottle, feeding on a rich meat 

 diet, becomes mature in a few days. As examples 

 of excessively long life-cycles the ' thirteen-year ' and 

 ' seventeen-year ' cicads of North America, described 

 by C. L. Marlatt (1895), are noteworthy. Certain 

 specially populous 'broods' of these insects are 

 known and localised, so that the appearance of the 

 images in future years can be accurately predicted. 

 Here again we have to do with bulky insects whose 

 subterranean larvae and nymphs feed on compara- 

 tively innutritions roots. 



In our own climate, it is of interest to notice the 

 variation among insects as to the stage which carries 

 the race over the winter. The click-beetles, men- 

 tioned just above, emerge from their buried pupae in 

 summer, hibernate under stones or clods, and lay 

 eggs among the herbage next spring. At the same 

 time of course, owing to the extended term of the 

 larval life, many more individuals of the species are 

 wintering underground as 'wireworms' of various 



