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.
Termidor SC is really designed to be used outdoors. Boracare would be best. The interior wood pieces that are exposed will have to be stripped prior to the application if they are painted or stained. The manufacturer has told us that Boracare is not corrosive and it should not harm the interior of the fiberglass that touches the wood. For more information you may want to contact Nisus directly by calling 800-264-0870