Cutworms.

Scratch around the plant stem in a circle usually no more than an inch or so deep and maybe 4 to 6 inches away from the stem and you should find an ugly gray worm an inch or more long.

The usual method for me is to put a cardboard "collar" around the stems of transplants such as broccoli, eggplant, etc. I use toilet paper rolls cut in half to form two collars. I push the end of the tube into the soil no more than an inch and it always works.

I don't bother protecting the beans since I plant them pretty densely and if I lose a few, I would hardly notice the loss.

When the stem starts to get tough, the cutworms move on.

Wayne

Yes, we've had cutworms get young beans, too. If the beans are very young and the stem is not cut completely through, we've had success taping the stem back together again. (This didn't work when I tried it on larger beans broken by wind, however.) One year we ended up putting collars around all the beans, as we normally do peppers and tomatoes, but the cutworm problem on beans is not generally severe. Be sure to look for the worms when you work the soil, and kill them.