I have a few planters on our patio on the roof where I plant, among other things, pole beans to provide shade. This year, however, all my beans are eaten by black beetles. What are they? They eat the leaves, in the same manner as slugs do, their larvae are white grub worms that chew on the roots. The beetles are quite soft and very sluggish, i.e., they don't run away when touched. Also, how do I control them?
Root Weevils? Not sure how you can control the larve, but you could hand pick off the adults in the evening when they come out. Vancouver has a city bylaw against anything I know that works. Jim