Just wanted to add beneficial nematodes to the flea arsenal (maybe it's already here somewhere). Several years ago, the big name flea treatment applied to the back of the pets neck just stopped working for us. We got infested. We used borax & DE in the house (too much carpet), but outside we used nematodes. I purchased a bulk supply with 3 types of nematodes and have continued putting them out every spring. These fabulous parasitic worms also kill June bugs, termites, fire ants and other creatures that spend at least part of their life cycle in the earth. Here in zone 7, I spray them 3 times @ 5 day intervals in early April.