I must admit to being Very naughty & using the R&*$$!£$ word on portland, but generaly yes we call them wilfies when there. I've also been led to beleive it's because they caused many Deaths when Quarries the'd dug there burrows in to collapsed.
I could of coure mentioned the other portland tales told in other parts of Dorset, but as the's a portlandlander here I'll resist the temptation. & leave you all guessing.
Other superstitions:- Cornish Miners whould always leave a crust of their tilie-ogie (pastie) for the mine spirits, to guard against death.