Q: I have several of these on my tomato plants and have no idea what they are. They don’t look like cutworms and they only seem to be eating the leaves. Can you help?
A: You have a tomato fruitworm. Although its name implies that it damages tomato fruit, it can also devour tomato leaves.
The easiest way to control it, as with any caterpillar, is with an organic spray containing B.t. (Dipel, caterpillar Attack, etc)
see Tomato Fruitworm