caterpillers
No - caterpillars are the larval stage of moths and butterflies - which belong to the insects group
no
No
According to the Noah Webster's Dictionary, the etymology of the word "caterpillar," is uncertain. Something you can get from it though is: the word "pillar", meaning a cylinder shaped column, is in "caterpillar", and as you know, a caterpillar is a little tube shaped guy.
No
Birds
yes
by eating plants
Yes they do. And many of them.
Not really.
not very well