I thought that I'd let everyone know that I finally identified the caterpillar that was hollowing

out my tomato stems. The name is Papaipema nebris, Common Stalk Borer. It seems that these guys attack brome grass, corn, giant ragweed, and sometimes tomatoes and potatoes. There's some ragweed in the field next to my garden, so I guess that's where the infestation originated.

April

Here is a link that might be useful: Stalk Borer