I have some tomato plants in a planter on the deck. I noticed 2 caterpillars on them. They are large (about 2 inches long) green with white sacks attached all over their bodies. I noticed black droppings on the deck under these bugs. The plant is producing plenty of fruit but seem a little wilted but I think that is more a factor of water (they dry out quickly in the planters) I have one plant out in the yard that apparently does not have any of these pests on there yet and it is doing fine. Anyone know what these are? Can I just kill them and be done with it or are more steps needed? Tom St. Louis, MO