I planted a bean plant which is putting out vines and doing great, except the annoying beetles keep on chewing up leaves, blossoms, even little bean pods. They're ladybug-sized (obviously not ladybugs), either brown, black, or a mix of these colors. I just want to get rid of them, but I only have insecticide. I now it's a bad idea to use insecticide on a plant that's going to produce beans I eat. I tried plucking each one off by hand, which is a tedious job. Is there any "safe" way to rid the bugs without using anything harmful to my health?