I never heard of any species of voles eating plastic & metal. That
really does sound more like rats.

Voles are pretty much vegetarians, unlike some other rodents. Voles are
super at eating bark off small trees and roots.

Did you get a good look at a corpse? Could they be cotton rats? I
think they are mostly a little smaller than Norway rats, shorter tails.
Not sure what you have in TX. But those are mostly vegetarian too, I
think.

Linda Mann east TN USA zone 7