I don't believe it to be a caterpillar at all. They look more like the larvae/pupae of a beetle...maybe a Colorado potato beetle? I wouldn't wait around for an ID, though. Yikes! Rather than experiment with a home made brew, I'd strongly suggest a spray of insecticidal soap directly on these little pests. Jean...what do you think these might be?

Jean, Thanks, that's it. The first thing I thought when I saw them is they look like a turtle. When I searched "turtle insect tomatoes" on Google earlier and saw tortoise beetles the pictures didn't look enough like this one. I did more searches and found a picture of the exact kind after I read your post. Will BTK kill them if they become a problem? In past years they were more of a problem on pepper plants and not tomato plants but I don't have any pepper plants this year. Thanks, Don

Groundhog damage sounds like to me, if no deer around. Squirrels usually just go for the fruit. Any sign of rat droppings? They will eat most of the plant. If you are living in town the choices are usually narrowed than for those of us out in the country. Dave

Damage from young grasshoppers looks like that. But 1) there's not much you can do about grasshoppers and 2) tomato plants aren't grasshoppers' favorite meal, so it's unlikely they'll do any significant damage.