>>96336295
Oh yeah, I can explain it.
It's all pseudo-biological and magical stuff, magic isn't an exact science, lots of stuff influence them (verms are only one of the different sistems there are, but one thas is easy to find as they tend to gather where magic is either "rotting/collecting" in miasma, or where high celestial magical is pure, wich are akind but not exactly verms), but I don't speak english very well so I will try to explain it. Salt is very good for the more impure, slimy ones, both because salt has ever been a good preserving and sacred mineral to use in real life, as well as they just work for stuff like slimes, slug to disecate them.
Iron is like that too, but iron I asociate it more with the death/underworld, and as well as it interfered with fey in legends, it does the same for the kind of verms than are more high "vibration", it mess with they magical fields so to speak.
And silver in my setting absorbs magic, so as lots of verms are what we would call low power, they just "dry" up of they magic and either go dormant or straight up killed or at least weakened. Silver being also used in lots of legends to deal with the supernatural doesn't hurts.
There are other ways (smells, like Rosemarinus Officinallis, Cinamon, Incense of lots of kinds), to atract them (pretty rocks, alchol, butter) etc