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.
For Termidor SC to work on Drywood termites, you have to drill directly into the piece of wood the termites are in and inject Termidor into the wood. Termidor does not penetrate into wood, so you have to inject it into the center. It has to touch the termites to work, but the benefit is that it only has to contact a few termites, and then they can pass it on to the rest of the colony.
For Drywood termite treatments on wood, we recommend applying a product called Bora-Care. This product is applied to raw wood and penetrates further than any other product.