A commonly recommended bug and grub control method is "hand picking". Ok, so that's just gross. I don't want to have to pick up bugs, let alone caterpillars! Too many wiggly legs! Fortunately, small boys (and some small girls) have fewer reservations about such things, and can be hired for a small bounty per bug. Give them a jar to put them in, let them cash in (a penny a bug, or a nickle if inflation has hit that hard). When they are done, let them take them to the ducks or chickens, or to the neighbor's pet iguana.