critter in the attic

They do make a copper wool. I found it in the same place as the steel wool pads.

In article , trswan1 @yahoo.com says... :) On our air conditioner, the refrigerant pipe goes in to the attic at :) the side of the house. Well, the foam insulation has been chewed off, :) exposing the copper tubing, and a nice size hole now goes into the :) attic. I know mice(?) don't like steel wool, but I can't put steel :) wool up next to the copper can I? :) :) Any ideas of what to plug the hole with that is difficult/unpleasant :) to chew thru? :) :) If the packing will be exposed to the outside, steel wool will create a rust stain, copper can create a blue stain running down the wall. Mice will usually look for the easier way inside and packing the void with any sort of caulking usually works well.

Chewed off inside or outside the attic. If inside, it is time to call in the critter control people.

I heard that rats will eat through steel wool but not copper wool. First you need to find out what kind of critter it is. Sorry to be so graphic, but have you seen any "calling cards" (droppings)? The size of the calling cards will usually inform you as to whether you are dealing with mice, rats, or something else. As one of the other posters suggested, it's time to call critter control.

Outside. Now it can climb up the pipe and get into the attic.

Sheet copper cut to fit around pipe and block apertures.

Barrel of a shotgun?