They’re about 2-3mm long with large wings. Last summer, I found maybe a hundred dead in the floor in my basement bathroom multiple times, which we usually keep closed. There weren’t any in the winter, and now they’re appearing again. Sometimes I get some sewer gas smell but I haven’t found any leaks anywhere. The basement bathroom isn’t used very often, only when we have guests staying with us which is rare. I’m worried a waste pipe may be cracked and is likely leaking into our vents, which are ducts in slab.
Here are pics of the flies if that helps. https://imgur.com/a/UmM0Woi
u/HoMi1208 — 19 days ago