What is eating the aluminum garage door trim
Thanks for the question.
There really are only two possibilities for this damage; chipmunks or squirrels.
I doubt that the damage is being caused by squirrels for two reasons. First, while squirrels do like to gnaw on things to wear down their incisors, they normally pick wood, not aluminum, on which to do this. Secondly, this damage is very close to the ground. Squirrels typically would not do this but higher up.
So, I suspect this is chipmunk damage. At this time of the year (early fall), chipmunks are preparing for their winter’s nap and are looking for inside structures to sleep and store food. They especially like garages for some reason. I’ve had chipmunks over wintering in my outside garage for years. The most immediate solution to your problem is to cover these holes with some type aluminum cover. Unfortunately, this may only be temporary as the chipmunk (I suspect that only one is involved as they are solitary critters) may simply chew through some place else. A more permanent solution would be to set out live traps with nuts in them near your garage. When a chipmunk is causing structural damage, you are permitted to do this. Within a few weeks, chipmunks will be starting their winter dormancy. By plugging the existing hole and/or by trapping them, you will discourage them from spending their winter inside your garage.
Lastly, you could obtain the services of a professional exterminator. There appears to be several such commercial enterprises in Chisago County.