Q: I have had skin rashes since early March. It took me two doctors' visits to confirm that they are rat mite bites. We called a pest-control company, which fogged every room in our house with cyfluthrin and sprayed the carpet and sofas with Suspend SC (deltamethrin) and Gentrol. The yard was sprayed with Eco Exempt (I do not know the chemicals it contains).

The company came back four days later to fog the kitchen one more time with the same fogger and also fogged the garage, as we were bitten in the garage doing laundry. For this second treatment, they also sprayed the backyard with 50 gallons of 8 ounces of Tengrad (permethrin) and 0.85 ounces of cyfluthrin.

A: In my opinion the pest-control company was incompetent to use all those chemicals (especially foggers) in an attempt to control rat mites. I would suggest hiring a pest-control company that will use food-grade diatomaceous earth.

This product is perfectly safe and could be blown into walls, attic areas and the crawl space. Not only will it kill the mites and any other pests in encounters, but it will also last for years. It is much safer and much more effective than the stuff that was used in your house.

Q:You mention diatomaceous earth frequently in your column. Will it also control termites?

A: It won't control them if they are already present in your home, but in some circumstances, diatomaceous earth will prevent subterranean termites from infesting the structure.

If you have a crawl space and there is no termite activity, you can have diatomaceous earth applied to certain areas to block them. The material will last for years and is much safer than any of the conventional termiticides. You can also use diatomaceous earth in slab homes under construction.

You spread the material along the foundation wall and around areas where pipes will penetrate the slab before the slab is poured, just as you would do in a conventional termites "pretreat."

I am aware of one company in California that can effectively prevent homes from getting termites using diatomaceous earth. You can contact me for its information.