There's no way to know for sure what kind of pests are eating your bean plants without seeing the insects or at least closely examining the damage. Below is a link to some UT Ag Ext Service publications that may be of help. There are papers about garden pests about 1/3 of the way down the page.

Have you tried simple insecticidal soap?

Here is a link that might be useful: UT Ag Ext Service Publications

Do you see any japanese beetles around? They are pretty heavy in my garden right now. They can chew a hole right in the center of a leaf. They are eating my Cannas but have not bothered anything else. I don't have veggies in my garden.

Rebecca

Do you have a good recipe for this simple soap? I've googled for them from time to time and find an enormous range of suggestions. I'd love to try something that has worked well in our area.
Thanks!

Any garden center or store that sells any type of gardening supplies should have insecticidal soap. I get mine from Home Depot. It's not that expensive, and buying it premixed is much easier than mixing things up. I don't usually have to use a huge amount, but, if I did, I might consider figuring out how to make it.