Answer: I am sorry about your beans. There are many beetles that might be called Asian beetles so unfortunately I am not certain which specific pest you encountered. However, if it is the bean leaf beetle you might try planting a bit later than usual to try to avoid their peak emergence time frame. Also, no matter what kind of beetle it is, make sure to thoroughly clean up all of the infested plants and debris to try to limit overwintering.
Here is more information on the bean leaf beetle including a photo. Of the controls listed in the article, Sevin or carbaryl would be appropriate for home use although it would not be considered organic. Hand picking early on can be helpful if you have only a small bean patch. You may need to cut and paste the complete url into your browser to make it work correctly.
You may also find the following report on organic control research done in Iowa interesting.
If it is not this beetle -- as I mentioned there are a number of different beetles -- I would suggest you work with your local county extension to identify the pest and based on knowing that, determine how best to control it. I hope your beans do better next year.
Q&A Library Searching Tips