CATERPILLARS 



The Defences of Caterpillars 



The ranks of the caterpillars are thinned by the 

 weather, by many birds, and by other harassing 

 enemies, such as the ichneumon flies which lay 

 their eggs in the juicy body. The risks that cater- 

 pillars run are so many that their survival is some- 

 times surprising. In the main it is secured in two 

 ways by sheer force of numbers and by many 

 different peculiarities which protect the cater- 

 pillars not merely from being swallowed, but from 

 being pecked at. For even a slight wound may 

 be very dangerous to a plump caterpillar. Hairy 

 caterpillars are left alone by most birds, though the 

 cuckoo seems to relish them. Not a few give out 

 offensive fluids, such as formic acid, when they 

 are touched. Some have an unpleasant smell, 

 and others are unpalatable. Some hide during the 

 day, others play 'possum when touched. Some 

 lash with their tail whips and strike " terrifying 

 attitudes." Many have come to resemble things 

 that are safe ; thus some are extraordinarily like 

 stunted twigs or little knobs on a stem ; others 

 are like little splinters of wood or the curled margins 

 of withered leaves ; others are coloured like the 

 flowers they feed on. 



The True Inwardness of Caterpillars 



But of all the interesting things about cater- 

 pillars the most remarkable is the central wonder 

 the great change by which the crawling larva is 

 broken down and built up again on a new plan, 



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