Likely what you’d imagine. They were larvae, small, fat worms with little short “beaks” for chewing wood, just like a grub. It was a very very faint rhythmic grinding, crunching sound that I just happened to notice one day. Almost thought I was imagining it.

Pun aside, this I’ve done. I could even hear the worms chewing during especially quiet moments. We put cherry slabs under clear plastic in the sun, then peeled the bark and smashed the larva with mallets. Not sure why my boss didn’t want to use borax.