In article .com,
ginnydudek wrote:
Leaves on my tomatoe plants seemed to be diappearing. I found 6 big
green catapillers and took them off. What are these? What can I do to
avoid them.

They are tomato horn worms. On a small scale, hand picking is easy. But
if they have little white disks attached to their backs, let them be.
Those are the cocoons of a small parasitic wasp which will soon hatch
and eat the horn worm from the inside out, and then go out to find
other horn worms to lay their eggs in. I have never had horn worms
around long enough to do much damage before the wasps take care of them.
A web search should turn up photos of parasitized horn worms for
reference.

--
Steve