Greetings all, I have an interesting garage built out of 2×4 scraps long ago. I added blue foam insulation to the outside and covered it with some shiplap siding from a local milling. Two or three years later I now see lots of blue foam dust piles on the inside, but only on the north wall. Would this be carpenter ants? Contractor ants? What beast burrows in blue foam? I will explore next summer, but as for now from the inside I see no sawdust and the outside is buried in snow. I presume this must have happened during the spring/summer months. Any ideas?