They do go after insects, etc. so I would be sure you have eliminated all of those first.
I wonder if your 'bugs' have become immune to your destructive methods?
Generally, if you eliminate their source of food, they will go elsewhere.
Good luck.
I use diazinon and that grub ex crap. Just read some website that suggests using something called Milky Spore, which is some bacteria that kills grubs and insect for up to ten years. Has anyone ever used this?