Socken mit bohrungen

I recently found one of the first socks I ever knit behind the dresser. It was made with one of those self striping yarn, that was pretty exciting for a knitting newbie.


But look at this, holes! Holes throughout the sock! I have no idea where they came from. Sometimes my clothes get holes in them from the washing machine here in the building but we stopped using that machine. So where could they have come from? I haven't seen any moths here at all. I'm concerned about my other wool socks...and yarn! Ideas?