Yes, for sure they are termites! There are wood frames in the greehhouse...they may be going after that. The greenhouse is metal, with a plastic liner...right now there are various greens in there. Going to transplant tomatoes, peppers and eggplants in there this week. I've read that orange oil, neem or borates can be used to treat. Not sure if i want to use that in my greenhouse...Diatomaceous earth is a good idea....