hope this works:


https://imgur.com/a/JGiKLDB



<blockquote class="imgur-embed-pub" lang="en" data-id="a/JGiKLDB" data-context="false" >




https://imgur.com/zTSF8kj

Copy the BB link code, paste in the reply box then hit submit.

too much moisture under your roof?

Watching too much granny porn?  

Pics not coming through, but took a shot anyway.

Taking a shot here... it looks like rodent or bird damage. Is there a fine mesh screen on the inner face of those louvers to prevent birds from flying in/out and nesting? It looks like a bird has been landing there and slipping through, the lower louver is more damaged from claws gripping it. The damage is localized bc birds are creatures of habit and as that wears down the hole/entrance will become larger there.

yep, above poster is right
woodpeckers/flickers

the hot air coming out attracts bugs, etc

best way is to change the vent out to a metal one.  

also 22 shorts have been mentioned by a friend...............................

Animal.

Birds, squirrels, etc.

One of my gable vents was stained in a similar fashion, then I started noticing droppings on the pavement below. I went up in the attic and discovered a colony of bats had moved in.  A few days later one of the little bastards wound up in the living quarters. I hired a wildlife removal company to get rid of them. They blocked all other entrance or exit points then put an excluder over that louver and waited 30 days to make sure they had all left the attic, they couldn't get back in with that device installed.

What had happened is they had roosted in the louver long enough for their urine to corrode the screen sufficiently to provide ingress. I couldn't believe how many of them there were.

Bats be my guess without going up there.

If its yours, go up and inspect. Or hire a pest guy to inspect to make sure nothing is up there.
If vacant, get to the hardware store and buy some screen mesh and secure it to the inside

Make sure the screen is metal, not nylon.

imgur doesn't come through the .mil firewalls, so between the no pictures and worthless thread title, I'm out.