Food or garden grade Diatomaceous Earth. Do not buy pool grade as it contains chemicals harmful to animals.
It is completely non toxic and is also used in spices to keep them from clumping. Sprinkle areas where the dog frequents ( doesn't take much!! ). I use a powdered sugar sifter. You can sprinkle it on the dog as well, kinda like a flea powder. I sprinkle it in the carpets, under furniture, outside.
Try to keep from inhaling the powder and keep it out of the eyes, nose and ears ( yours and the dog's) It will not hurt anything for the dog to eat it, but I don't recommend feeding the dog large quantities
The principle behind the DE is the particulate is smaller then the crevices in the insects' exoskeleton. It basically dries the little buggers up from the inside out.
Last time I checked, you can get it in basically any hardware store. I know how hard it is for you guys, but you might have to ask for help finding it
Melissa ( Walter's better half )