LETTERS ON ENTOMOLOGY. 45 
some part in it. These moths are also found in 
England : the caterpillar is yellow and green, and 
has a strongly curved horn on the tail. Nature 
varies no less in size than in form, as we may see 
in the difference between the great Indian butter- 
fly, which is several inches across, and the little 
white one which feeds on the cabbage, and is 
hardly so big as a pin's head, yet it has a trunk 
which does not roll up, but is protected by a 
sheath ; this little creature is only three days in 
the form of a chrysalis. 
From some kinds of caterpillars we may learn 
the good effects of living in harmony and fellow- 
ship. One of the commonest kinds, of which the 
eggs are laid by hundreds in the same place, and 
which come out nearly at the same time, range 
themselves in regular rows, and feed in perfect 
order, never interfering with each other ; which 
if they were inclined to do, would make sad 
confusion. They also work for the public good ; 
for as they go on eating the upper surface of the 
leaf, which dries and contracts, forming a kind 
of cavity, they draw silken threads across from 
side to side, till a tent is formed, into which they 
retire for shelter. They live principally on pear 
and apple-trees. These do not disperse till they 
have frequently changed their skin. 
