Have you checked at night with a flashlight? I don't see slugs or snails during daylight but baiting sure kills them. If you find them in the evening or early morning; a spray bottle with dilute household ammonia will kill them and the ammonia becomes nitrogen.

Yes, likely slugs.

And tell whoever mis-informed you that aphids don't make holes. Not ever.

Beer traps are a good way to deal with slugs.

FataMorgana

Thank you very much. But I wonder if slugs are not too big to get on thymes. They normally get on large leaves like those of hydrangeas. But how do they climb up thymes (mine are upright ones) eat the tiny leaves? Don't they have to be able to sit on leaves to be able to eat them?

A