We killed 8 wasps in the house yesterday and finally figured some things out. (1 in the kitchen, 1 in the bathtub, 3 on the landing and stairs, 3 in the attic when we went up to have another look.)
We’ve narrowed down the wasp location problem, and how they’re getting in. Nothing to do with the windows or vents. They’re entering and exiting under roof tiles. The nest is somewhere hidden in the roof insulation probably near the water tank in our attic. The crawl space up to the attic is actually sealed pretty well, but they’re getting out into the house through the light fittings. What we hadn’t noticed previously was that the bathroom light (an enclosed globe) has a pile of dead wasps in the bottom of it. (They’re not so visible when the light is off, and we don’t tend to look straight up into a light that is turned on because ow bright.)
The problems with the nest location: 1) we can’t actually see or hear it. Most wasp nest solutions involve sealing it up or basically putting poison at the opening. Which means they need to be accessible. Mr lurker bought some powder and spray, but 2) its most likely location is near our water tank and we’re not putting poison around our water tank for obvious reasons.
Doing the reading up on wasp nests, they should be at the last social phase and die off soon as the weather gets properly cold. If there’s a warm spell in the winter the new queens should fly away to form their own nests somewhere else. So, our best bet appears to be to wait them out and hope they all die soon and our little niece doesn’t come to visit and try to swat the flies in the meantime, because hiring an exterminator would mean tearing out all our under-roof insulation just as winter sets in. We’re looking for a flush fitting for the light above the stairs that we can put in in the meantime.
ETA: 3 today before lunch. 1 crawling in the bathroom, 2 already dead by the front door. Must remember to wear hard-soled slippers at all times for a while or be very careful where I step.