I'd bet my bottom dollar it's Earwigs.

A very effective bait is equal parts of soy sauce, oil and molasses. The molasses is bait to attract them--the oil doesn't allow them to crawl back out and the salt in the soy sauce finishes them off. Put it in a small container and bury it up to the brim. Prop a lid over it so it doesn't get diluted by rain and so it is a nice dark place for them to hide--ha. You might have to wait a couple of days for it to work but it does work. Your container will be full of them.

If you go through this website you will find lots of testimonials to this method

Thanks for the suggestion! I'll try it.

If the holes are small they may be caused by Flea Beetles. Holes about the size of a pencil lead. Earwigs if larger than that. Al

They're on the larger side, so I think probably earwigs. Thanks.