Fake owls and snakes are of no help. Chipmunks will risk anything to get a ripe tomato.

I only had 20 plants but was dismayed that all the bottom tomatoes had their bottoms eaten out the day they became ripe. I put out a couple of Have-A-Heart traps (wire cage with trapdoors at each end).

Don’t bother with peanut butter on apples etc. No self-respecting chipmunk will go for that if ripe tomatoes are nearby. Cut up the ones they have already damaged and use that as bait. I trapped 12 in 10 days and then was able to eat tomatoes without worry that they would beat me to them. I was hauling them off every morning seemingly w/o end, but they eventually ran out of replacements.

I took them to a nearby park and released them in the same spot, 1 or 2 a day. Nearby means at least a mile or two away. Check the traps every morning or risk them suffering sunstroke.

Oldtimer

One day I picked up a fallen tomato and on the other side was a small brown caterpillar, with a black dot on either side of it’s head and teal stripes running down the sides, chomping away. The hole he created was impressive for a little guy, a larger one could have easily done the damage in the photos above. On a different tomato plant I did find a cocoon of a large caterpillar, about half the size of my pinky. No doubt that guy could have been the cause of my damage. He was dead and grey so I don’t know what color he was before he bit the dust. No damage found after that.
Last, I did find 6 green caterpillars on my cabbage, which is planted in the row next to my tomatoes, I suppose they could have made pilgrimages but I doubt it, they seem content with the cabbage based on the damage.
We’ve recently found two brown widows in the house, which is strange for those types of spiders, and one in my 9 month olds bedroom! We yanked everything out, sprayed and called it a year. Until spring my friends, happy hunting.

Could this be the culprit?

Brad, it sounds like you are describing a potato bug. Is that what you found?

we got some nasty bites out of one of our tomatoes just yesterday and think it was a rabbit who jumped up to the topsy turvey. (took photos)

We saw evidence of additional horn worms, but couldnt find them. We bought BT Bacillus thuringiensis and used a few drops in a quart sprayer and instantly found two VERY unhappy hornworms squirming. I would recommend this safe product to everyone.

The tomato season here in San Diego is going, but definitely seeing a slow down, so we don’t have too much time yet.