2-2 TIIK LIMvSToKY OF INSECTS [CH. 



its behaviour resembling that of a butterfly pupa. 

 The adult winged male (fig. 7 a) leads a short, but 

 active life. 



Another family allied to the Aphidae is that of 

 the Cicads, hardly represented in our fauna but 

 abundant in many of the warmer regions of the 

 earth. Here also the young insect differs widely from 

 its parent in form, living underground and being 

 provided with strong fore-legs for digging in the soil. 

 After a long subterranean existence, usually extend- 

 ing over several years, the insect attains the penulti- 

 mate stage of its life-story, during which it rests 

 passively within an earthen cell, awaiting the final 

 moult, which will usher in its winged and perfect 

 state. 



In the life-histories of cicads and coccids, then, 

 there are some features which recall those of the 

 caterpillar's transformation into the butterfly. The 

 newly-hatched insect is externally so unlike its parent 

 that it may be styled a larva. The penultimate 

 instar is quiescent and does not feed. But while the 

 caterpillar shows throughout its life no outward 

 trace of wings, external wing-rudiments are evident 

 in the young stages of the cicad. In the male coccid 

 we find a late larval stage with hidden wing- rudi- 

 ments, the importance of which, for comparison with 

 the caterpillar, will be appreciated later. 



