Got worms in my wood, need advise.

[HARRYWALLY]

My Dad found a Birch rough cut slab in a friend's barn. Been there for many years and is dry as a fart. He's making a natural edge side table out of it, but has noticed that there is still active worms in the piece. As you can see, he has it sanded and stained already. Notice the fresh saw dust from the worms. How can we get rid of these dang worms!!!

Any ideas from the experienced would be great.