Probably Mexican bean bettles. I'm getting some holes in mine too. For now will just use the pick and smash method. Often smash them right on the leaves as to give a message to its friends. The bean beetles like to drop when you try to catch them. I place one hand under the leaf and pick the beetle with the other hand. The pest usually drops right into my catch hand and meets his/her end. If you don't care to smash the critters, hold a small container of alcohol under the leaf and then they will fall or you can just drop the bug into the alcohol. Virgorously growing plants will usually do o.k. in spite of a moderate bean beetle attack, so for a modest home garden, hand picking works just fine.
Eclectic gardening style, drawing from 45 years of interest and experience. Mostly plant in raised beds and containers primarily using intensive gardening techniques.