WTF! I am totally stumpped. Home at lunch to check on things, noticed a fly or two (common house fly not gnats or any thing else). Kinda thought "I wonder how those got in?", but didn't think much else. Came home after work and there were at least 25 buzzing around (I know cause I hunted them down). Then it was like "What the hell is going on?" Killed them until there were no more to be found. Checked again a couple hours later and they are thick again. I really can find no obvious way in and there are no stragglers anywhere else in the building. Do houseflies reproduce in soil? There is no other waste or food source with the exception of dry amendments for TLO style soil grow. I think with the exception of disease transmission or as another pest vector the thought of them is probably worse than anything they could actually do-I hope. Any relevant feedback (or irrelevant if entertaining) would be appreciated. I have sticky sheets around and made a ghetto flytrap for now.