What's eating my petunias?

I have two flower boxes on my deck, both with beautiful, healthy petunias. All of a sudden over the last three days, the box on the left seemed less bountiful. I investigated and found a gazillion small nibbles on all of the flowers %26amp; buds. Clearly the work of some insect. I searched everywhere for caterpillars, slugs, etc. and found nothing. The box is too high for a rabbit to be the problem. And the flower box on the left is still in great shape with only a few small nibbles on a couple of flowers. Anyone have any suggestions on what I should do????

What's eating my petunias?
It's probably snails and slugs. They're good at hiding. Try looking at the plants using a flashlight at dusk (9pm-ish), and you'll catch 'em if that's it. If it is, you can either pick them all out by hand and squish them, or get some snail bait. "Sluggo" is a good brand that's considered safe, as it's not really a poison (except for snails and slugs). You can also buy strips of copper to put around the edge of the window boxes, as that will repel them, but if the snails are inside already, this won't help much.
Reply:I suggest checking after dark. There are beetles that fly around after the sun goes down and eat various plants and flowers. That could be your culprit. You can spray for them, but I found that handpicking them off works best.
Reply:try your next door neighbors . i think it is that thing!!
Reply:Could be slugs. Sprinkle bug Getta, or some people say put a shallow dish of beer out, and they will go into the dish and drown. Sounds gross to me, but they swear by it. I like the Snail and Bug Getta. By at your local home store.