Diatomaceous earth cuts the exoskelaton of insects. There is no set time limit to effectiveness but it is non-toxic. It is used in pool aquarium filters, pool filtration systems, etc. Some garden centers will carry it for orgainic gardeners. I am not going to tell you it is going to cure all your insect problems but it won't hurt. Texas scorpions aren't really terrible unless you are allergic. The stings will hurt but aren't the horror story on the evening news either. If you are really worried, get a black light (UV light) to look into your shoes and tight areas. Scorpions will glow (no matter what color the scorpion is) which is kind of awesome when you think about it.