I think you may be referring to tomato hornworms, angelmama. Those things are hideously ugly. They suction onto your plant and are difficult to see because they are like chameleons. They eat all the foliage off your plant almost overnight. We had them a few years ago. I look for them each year now. There is a beneficial insect that is a parasite to the hornworm. It is called a Braconid wasp. It lays eggs in the hornworm. If you find one that has white eggs sticking out all over it's body, leave it alone. The white eggs are baby Braconid wasps. The hornworm turns into an ugly brown moth. Google for an image. If I see these in my yard I kill them.