Our first tomato growing season (2005) brought dreaded green hornworms that ate leaves and burrowed into our precious tomatoes. They came with the heirloom Cherokee Purple and the patio tomato plants we bought at the Union Square Green Market and quickly moved on to the rest of our crop (even the cherries Mitch raised from seeds.)
Well, we went right to the Web and found out what these critters were. We headed to a plant nursery in Long Island (we were there for the weekend coincidentally) where they suggested we try an organic compound called Safer, that's pretty widely used. We were leary of using any pesticides, but we didn't want to lose the plants so, we mixed and sprayed. The Safer was fairly effective at controlling the tough to snuff critters. We also kept a vigilant eye out for them under the leaves so we could pluck them off and squash them too.