BEETLES 343 



(a) The grub, in fact, has a vermiform shape, resembling both a 

 caterpillar and an earth-worm. Hence, it possesses a form of body 

 equally adapted for the reception of a food poor in nutriment (see white 

 cabbage butterfly) as well as for locomotion in the soil (see earth-worm). 

 Prom the caterpillar, however, it is distinguished essentially by the 

 absence of abdominal or pro-legs. Indeed, living in the soil, which 

 supports it on all sides, the larva does not require these aids to locomo- 

 tion. The only limbs present are 



(b) Three pairs of thoracic legs, which are long and weak, and conse- 

 quently not adapted for burrowing and scraping. (What is the shape of 

 fossorial legs ?) For these purposes the larva employs 



(c) The powerful pincer-like mandibles. The action of these may be 

 seen by putting a cockchafer grub into a glass vessel containing earth.. 

 If the earth is loose the animal scrapes it aside with the outer edge of the 

 mandible ; if it is firm, it bites the soil loose bit by bit with these organs. 

 The pieces of soil thus loosened are pushed backwards by the help of the 

 thoracic legs, and also with the head, the animal turning its body round 

 for the purpose. The powerful mandibles are also used for gnawing 

 hard roots, and, as in the case of a caterpillar (see white cabbage 

 butterfly), require 



(d) Firm supports, which are furnished by the hard skeleton of the 

 head. Being used,, moreover, as a burrowing instrument, it is necessary 

 that the head should be provided with a hard covering, in contrast to the . 

 remaining soft portion of the body. 



(e) Like most animals living beneath the soil or in the dark (give 

 examples), the larva of the cockchafer is devoid of eyes and of white colour ; 

 only the head and legs are yellow, being more strongly chitinized. The 

 egg and pupa are also white. (Contrast with the developmental stages of 

 insects which live in the light.) 



C. Place of the Cockchafer in the Economy of Nature. 



Leaves and roots being, as already mentioned, of small nutritious 

 value as a food, it follows that the cockchafer as well as its larva are 

 creatures of insatiable voracity, and hence highly injurious animals. In 

 so-called "May-bug" years large numbers of fruit and forest trees 

 are frequently despoiled of their entire foliage by these beetles. Still 

 worse is the damage done by the grub, which by gnawing at the root 

 destroys the whole plant, and thus ravages extensive fields, meadows and 

 plantations. Unfortunately, there is only one animal, viz., the mole, 

 which can get at these pests in their subterranean retreats. It there- 

 fore deserves to be well protected, like the rooks, which pick up large 



