SILK-WORMS. 
17 
mankind. He would not allow the existence of 
any caterpillar, except the silk-worm, and a few of 
those beautiful and bright-winged butterflies, 
which ornament our museums and delight the 
naturalist. 
The labourer dwells little on final causes ; he 
imagines nature must act for him alone ; he is 
ignorant of the harmony and variety which exist 
in the infinity of objects that compose the uni- 
verse. 
But although caterpillars do much mischief, 
nature having assigned them a specific employ- 
ment, has prescribed limits to their increase 
that they might not injure us too deeply. An 
innumerable quantity of these insects are natu- 
rally destroyed every year in three ways, besides 
the numbers which men may destroy by artificial 
means. 
1st. Numerous tribes of birds feed upon the 
caterpillars they find on trees or on the ground, 
either when just hatched from the eggs, or when 
they are grown larger. 
This food, which birds particularly like, and 
with which they rear their young, attracts them 
to the woods, the fields, and gardens, and they 
seek, with peculiar avidity, for the eggs of cater- 
pillars. 
2d. Among the various species of caterpillars, 
there are some that feed upon each other, with- 
