Mix up some boric acid(borax)and water in a spray bottle and spray them down. Do a test area first as it may stain the wood. This is the least harmful to wood and environmentally friendly method I have heard of. Don’t store those near or in your house/or workshop until you are convinced they are all dead. Those deadbeat tenants do nothing but destroy your house and they’re not paying any rent. I personally would not use the boards at all. I would take them to the landfill. Or have a nice fire. Termites are a colonizing insect that can burrow into the soil and destroy every home in their path. They consume cellulose (wood). Oak is a delicacy for them. Worse than cockroaches.