Life in the Cambium Layer

Seems that I can't pick up a piece of firewood these days without getting distracted.  Busy writing when the house got a little cold.  I figured five minutes to load the wood stove wouldn't interrupt the flow, but I was wrong.  When I saw these beetle tracks on the first piece of firewood I picked up, I started daydreaming about life beneath the bark.  As the larvae chew their way around, how do they decide when to make a left or right turn?  Do they ever get curious enough to chew toward the surface or deeper in?  Maybe they're just hooked on the tastiest layer and are not capable of curiosity.  Of course curiosity can be a blessing or a curse.  I forgot what I was writing about.