I know that termites will eat almost any wood, but prefer some over others. Where does OSB rate on termite's list of preferences? Will they eat it before redwood, or after? How does it rate compared to fir?
Living in Ca you have plenty of advice around locally.
Termites in your neck of the woods are very bad as you may already know. They love Oriented strand board, and plywood, and anything having to do with wood. Some species of wood are not preferred, but I have even seen them eat pressure treated.
They also like styrofoam board, so talk to the locals about your type of varmints. That is where you will get the best advice.