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THE INSECT WORLD. 



Memoirs to observations on the skill with which divers species ot 

 caterpillars fold, roll, and bind the leaves of plants and trees, 

 especially those of the oak. Let us listen to the great observer : 

 " If one looks attentively at the leaves of the oak tree towards the 

 middle of the spring, many of them will be seen to be rolled in 

 different ways. The exterior surface of the end of one of these leaves 

 has, it appears, been rolled back towards the interior surface, in order 

 to describe the first turn of a spiral, which is then covered by many 

 other turns (Fig. 282). Some leaves are rolled towards their exterior 

 surfaces, others are rolled towards their interior surfaces, but in a 



Fig. 282. Oak leaf rolled perpendicularly. 



Fig. 283. Oak leaf rolled sideways. 



totally different direction. The length or axis of the first roll is 

 perpendicular to the principal rib and to the stalk of the leaf, the 

 axis of the latter parallel to the same rib (Fig. 283). Work of this 

 kind would not be very difficult to perform for those who had fingers; 

 but caterpillars have neither fingers nor anything equivalent to fingers. 

 Moreover, to have rolled the leaves is only to have done half the 

 work : they must be retained in a position from which their natural 

 spring tends constantly to draw them. The mechanism to which the 

 caterpillars have recourse for this second part of their work is easily 

 perceived. We see packets of threads attached by one end to the 

 surface of the roll, and by the other to the flat surface of the leaf. 



