The active ingredient in Termidor SC, Fipronil, works by disrupting the insects central nervous system by blocking GABA-gated chloride and glutamate-gated chloride (GluCl) channels. This causes hyperexcitation of nerves and muscles in insects.
Termidor applied in a trench really helps to prevent pest that are traveling through the soil. It sounds like you will need to re trench since over 10 years and then spray around the foundation 1 foot up and out with Termidor. You may also want to use apply dust like Delta Dust into wall voids for the spiders and other pest.
You should perform a liquid termite treatment in the ground to get the termites where they are entering your house. To perform a treatment just as a professional company would do, please read our How To Do A Termite Treatment Article which explains exactly how you should treat your home properly. Doing a treatment like what is described in the article will not only take care of existing termites that you have, but it will also protect and prevent future termites from entering for about 7 years.Here is a a link to the article: http://www.domyownpestcontrol.com/termite-treatment-c-3_352.html
You do not have to treat all of the hollow block walls, only the bottom 2 where the termites could come through the soil with Termidor SC.
In the areas where you cannot treat with a liquid treatment such as Termidor, we would advise using a termite bait station such as the such as the HexPro Termite Baiting station. This will help you keep areas that cannot be treated with the liquid treatment monitiored.
Termidor SC can only be applied one foot up and one foot out directly around the exterior of a structure 2-4 times per year or in a trench for termites. It should NOT be applied indoors or to trees, plants or lawns.
Insecticides should not be exposed to extreme temperatures such as freezing or over heating or left for prolonged periods of time in direct sunlight. In the case of Termidor SC, after it has thawed at room temperature if it goes back into a solution (the way it looked at the time of purchase) it should be fine to use. However, if it appears discolored or if the consistency of the product has changed it should be discarded and replaced.