Found some weird tunnels in my attic insulation, should I be worried?

Those tunnels are a classic sign of mouse activity, but it doesn't necessarily mean you have an active infestation right now. Mice love blown-in fiberglass because it’s easy to burrow through and holds heat well. The staining you're seeing near the orange foam is often what we call **rub marks**—oily residue from their fur as they squeeze through tight gaps near the framing. Even if you don't see them currently, they definitly spent some time there at some point.

If you aren't seeing any rice-sized droppings or hearing scratching at night, you're prolly looking at old damage. Mice are incredibly messy. If they were living up there currently, you’d see black pellets scattered near those holes or along the top of the joists. Since you mentioned the bug issue was handled, it's posible the previous owners sealed the main entry point and the colony died out or moved on a while ago. To be certain, set a few snap traps baited with a tiny bit of peanut butter right next to those tunnels. Check them after two or three nights. If they stay empty, you’re likely just looking at a ghost from the past. But you should still do a quick walk-around of your soffits and gable vents. Any gap the size of a dime is an open door for them. If you find one, stuff it with **copper mesh** or steel wool before foaming over it so they can't chew back in.

As for the insulation, there's no need to call a pro or replace anything if it's just a few tunnels. You can just use a garden rake or even a piece of scrap wood to lightly fluff and level the pink stuff back out. Just make sure you're wearing a proper **N95 respirator** and long sleeves. You don't want to be breathing in fiberglass particles or whatever old dander is trapped in those burrows.

That rake idea makes sense, but does leveling it out hurt the R-value? I’ve heard you’re not supposed to compress the pink stuff or it stops working as well. If I’m just fluffing it back over the holes, am I safe? Also, regarding the copper mesh, do you just shove it in the gap or do I need to staple it down or somthing? I’m worried a persistent mouse might just push it right back out if it’s not anchored.

Fluffing the pink stuff back up actually helps. R-value is all about those air pockets, so as long as you aren't mashing it down with your knees or heavy tools, you're golden.

For the copper mesh, I usually jam it in with a screwdriver and then hit it with a bead of spray foam. The foam acts like a glue so a mouse can't just nudge it out. Since you mentioned staining near the orange foam, that’s a classic 'air bypass.' Even if there aren't mice now, that spot is probly leaking heat from your living space into the attic. Seal it tight while you're up there.

Keep an eye on your ductwork too. In my last house, the mice didn't just tunnel through the floor insulation; they shredded the outer wrap on the flex ducts to build nests. If you see any silver foil or plastic hanging loose near the AC unit, give it a close look.

Since you're in SC, those attics get like ovens in the summer, so they prolly only bunked there during the 'winter' months. If you find any random debris like acorn shells or bits of candy wrappers, that’s a dead giveaway they were staying for more than just a quick visit.