You can make a good, organic, home-made pest repellent by catching a bunch of the bugs you want to eliminate – Japanese beetles, say – and put them in a blender with enough water to smush up all those crinkly, buzzing parts into a liquid you can spray out of a plastic spritzer bottle.
Then spray the infested plants as needed. What happens is that new Japanese beetles fly happily in, only to discover the leaves are coated with a diluted mix of their parents, nieces, and cousins, which is decidedly off-putting, and away they go.
Just one thing: Do not use your wife’s favorite blender or juicer. Trust me on this.