Are carbohydrates ok for mammals?

Yes, Jim.

Yes, Elna.

Pine bark mulch is OK for earthworms, in that it won't kill them. It will actually provide some beneficial cover and insulation from the winter elements. As it breaks down in a couple of years, the earthworms will like it much better.

If your goal is to benefit earthworms, they would be even more appreciative of a softer "forest floor" environment like shredded leaves, hay, or pine needles - especially with some used coffee grounds or kitchen scraps mixed in.

But if your goal is to get rid of pine bark mulch without harming the worm population, then you can sleep soundly knowing that the worms will be happy underneath the bark.