74 ON SOME LEPIDOPTEEOUS LARV^ 



The business of the larva or caterpillar is to feed and 

 grow, to build up a supply of energy which shall carry it 

 through the long pupal sleep and equip the perfect insect 

 with the strength to guide its rapidly moving wings through 

 the air. In some of oar most powerfully flying insects the 

 mouth-parts are so imperfectly developed (as in our Oak 

 Eggar or Fox Moths) that no food is taken in the imago or 

 winged state, consequently the organism has to depend on 

 the stored-up energy inherited from the days of its larval 

 growth. But as the larva has so much work to do, a 

 voracious appetite constantly requiring food, it is generally 

 slow in its motions, and in many cases scarcely moves at all, 

 whilst its supply of leaf-food remains unexhausted. Hence 

 in this stage, usually of long duration, it is always more 

 or less open to attack by the great enemies of the lepidoptera 

 — the birds. 



. Their bright eyes are constantly on the watch, and the 

 poor larva once detected is soon seized by the sharp bill of 

 its dreaded foe. Thus, were the larvae not protected from 

 their enemies in manifold ways, even the vastly prolific races 

 of the insects would soon dwindle under the persistent 

 attacks of their destroyers. Yet such are the beautiful and 

 varied devices by which caterpillars are protected during 

 the stage of insect life most marked by danger, that it is 

 rarely that the equilibrium of Nature is greatly disturbed. 



Where species are becoming rare or have entirely dis- 

 appeared in England, the cause generally lies in some act of 

 man or modern civilization, which has altered the face of the 

 country or destroyed the food-plant of the insect. Of this 

 we have a notable instance in the drainage of the Fens 

 of our eastern counties, which has led to the total exter- 

 mination of our Large Copper Butterfly, and the disappear- 

 ance from England of Loelia Coenosa and other insects. 



