I'd like to know what long lasting chemical I can use around our pier & beam foundation to insure that termites don't come around. I have a friend that has the license required by our state for restricted chemicals so that won't be a problem. I have heard that the use of nematodes is a termite deterent. If that is true, what specifically do I need to do to insure that they continue to thrive & reproduce in our ground?

Get free estimates from exterminators in your area. Most of them will tell you what they will use while they try to sell you their service. They'll also explain why do-it-yourself is a really bad idea with termites.