When I moved into my house five years ago I had lots of ladybirds spending the winter in my bathroom. They just slept in little clusters in the corners of the windows and walls and were no bother. Once spring came they just flew off.
The next summer, the one before Covid, my back garden was plagued with flies- so was my neighbours. I had so many flies it put me off sitting out in the garden.
The following year I had no ladybirds or flies but last year the wasps came! I couldn't see their nest but they just appeared from nowhere in my bathroom but never flew anywhere else in the house.
This winter the ladybirds are back!
I wonder if I have some sort of microclimate going on here, that goes in cycles.
Maybe the flies will be back this summer, who knows, it's all a bit strange but fascinating.