3i6 



Microscopical Essays, 



Different fpecies of caterpillars are often to be found in great 

 numbers on the fame tree or plant : but then as they feem to 

 have no connexion with each other, and the actions of the one 

 have no influence on the other, they may be confidered as 

 folitary ; but there are others who feem ftill more independent of 

 each other, and greater friends to folitude, conftru&ing a lodg- 

 ing, formed of leaves tied together with considerable ingenuity, 

 in which they live as in a hermitage. The operation by which 

 thefe tie the leaves together, is far furpafled by another kind, 

 who fold and bend one part of the leaf till it meets the other. 

 Thefe are again exceeded by thofe who roll the leaves which they 

 inhabit. For this purpofe, the caterpillar chufes a part of a leaf 

 which it finds in fome degree bent : here it eftablifhes it's abode, 

 and begins it's work, moving the head with great velocity, in 

 a curved line, or rather vibrating it like a pendulum, the mid- 

 dle of the body being the center on which it moves. At each 

 motion of the head a thread is fpun, and fixed to that part to 

 which the head feems to be applied. The threads are extended 

 from the bent to the flat part of the leaf, being always adj idled, 

 both in length and ftrength, to the nature of the leaf, and the 

 curvature which is to be given to it. 



M. de Geer attending to the operations of a fpecies of this 

 kind of caterpillar, obferved, that at each new thread it fpun, the 

 edges of the leaf infenfibly approached to each other, and were 

 bent more and more, in proportion as the caterpillar fpun new 

 threads ; when the laft thread that was fpun was tight, that which 

 preceded it was loofe and floating in the air. To effeft this, the 

 caterpillar, after it has fixed a thread to the two edges of the Jea£ 

 (and before it fpins another) draws it towards itfelf by the hooks- 



