SILK-WORMS. 9 
table substances, most of which are useful to 
man. 
We often have the mortification to witness the 
destruction of fruit trees, of kitchen or pleasure 
gardens, hedges, woods, &c. &c. Often also these 
insects, either not finding leaves, or preferring 
other things to them, destroy buds and flowers, 
attack fruits, lodge in them, spoil them, and cause 
them to fall off. Many kinds of caterpillars insi- 
nuate themselves into the earth, attack the roots 
of herbaceous plants, shrubs, or great trees, and 
make them unhealthy; to the no small astonish- 
ment of the agriculturist, w r ho sees his trees decay 
without any apparent cause. 
Some caterpillars live in the trunks of trees, 
wound them, piercing them in a thousand ways, 
and causing them to die prematurely. 
We find also frequently swarms of almost invi- 
sible caterpillars in corn, of which we become 
aware only when we see gnats in the granaries, or 
the grain itself rendered more or less light, accord- 
ing as the insect has more or less eaten it. 
Sometimeswefind the grain quite empty, though 
of a good appearance, because the caterpillar, 
which has entered by a small hole, eats only the 
flour, leaving the husk untouched. In a single 
grain, the caterpillar finds sufficient nourishment 
to support all its changes ; which leads one to sup- 
pose that when we find grains, the flour of which 
