EXAMPLE OF DIVERSITY OF OPERATIONS. 175 
caterpillars, feed upon the leaves; others upon the 
flowers, or on the fruit; a few will eat nothing but 
the bark; while many derive their nourishment only 
from the internal substance of the trunk. Every 
part of the tree is thus seen to supply food “ in due 
season” to all these diversified tribes. If we examine 
further, new modifications of habit are discovered. 
Those insects, for instance, which feed upon leaves, 
do not all feed in the same manner, or upon the 
same parts: a few devour only the bud; others spin 
the terminal leaves together, forming them into a 
sort of hut, under cover of which they regale, at 
leisure, upon the tenderest parts; some, apparently 
even more cautious, construct little compact cases, 
which cover their body, and make them appear like 
bits of stick, or the ends of broken twigs; some eat 
the outside of the leaf only, while others, —like the 
caterpillars of New Holland, mentioned by Lewin, 
—bore themselves holes in the stem, into which 
they carry a few leaves—sally out during the 
night for a fresh supply, and feed upon them at 
their leisure during the day. It seems, in fact, 
impossible to conceive greater modifications than 
are actually met with, even among insects which 
feed only upon leaves; while other variations are 
equally numerous in such tribes as live upon other 
portions of the tree. Hence it is apparent, that in 
accurately determining the habits and economy of 
insects, no less than of animals generally, the greatest 
nicety of observation is absolutely essential. 
(119.) If we look to the feathered creation, we 
shall find an equally remarkable diversity of habits, 
even among those tribes whose food consists en- 
