36 LETTERS ON ENTOMOLOGY. 
resemble the perfect insect in form, but are 
equally capable of eating and moving. 
After remaining a certain time (some species 
only a few hours, while others remain months 
or one or more years in this state), the perfect 
insect bursts its case and enters on the last stage 
of its existence. 
Look at the elegant and volatile butterfly, 
which seems born but to flutter in the sun- 
beams, and regale itself with the pure nectar of 
flowers. It did not come into the world as you 
now behold it. At its first exclusion from the 
egg, and for some months of its existence after- 
wards, it was a wormlike caterpillar, crawling 
upon sixteen short legs, greedily devouring leaves 
with two jaws, and seeing by means of twelve 
eyes, so minute as to be nearly imperceptible. 
You now see it furnished with large wings ; ten 
of its legs have disappeared, and the remaining 
six are quite unlike the former ones; its jaws 
have vanished, and are replaced by a curled up 
trunk or proboscis, capable only of sipping 
liquid sweets : the form of its head is entirely 
changed, two long horns project from its upper 
surface, and instead of twelve minute eyes you 
behold two, very large, and composed of at least 
