Oldish empty coop, what would cause this?

[WindyRoost]

I got rid of my chickens two years ago and my coop has set empty since. I’m getting it ready for chicks and just found this (frass??)when I took the ceiling panel down. What would cause this? The old hens were part of a massive flea problem which is why they had to go in the first place. I never saw evidence of mites, although I did hunt!

 

[Debbie292d]

It does look like termite or some type of bug frass.

Mites need a host, so they wouldn't be living in there.

I'd use an insecticide first, then a disinfectant. Perhaps you could look into fumigating it or putting out termite baits.

When done, a good airing out prior to putting any chicks in there.