Damaged Paper to Insulation

What do you think caused the damage to the paper to the insulation?

There were numerous rodent baits & ant traps throughout the attic.

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Looks like the insulation is installed backwards anyhow.

Rodents and ants.

Does not look like the work of rodents to me, they chew and tear strips for nesting material. Ants don’t eat paper, as far as I know. Maybe moths, caterpillars, or larvae of some kind?

Unless it was double sided, but that was my thought as well.

A lot of earlier fiberglass and rockwool batts were double-sided with an asphalt based coating on the interior stapling flange side and simple thin brown paper to the outer side. Usually in this simple a situation, even if the vapour barrier were on the theoretically wrong upper side, no problems would occur unless you had an incredibly wet house below. In this case, many other problems would have shown up first.