Wasp invasion.
They built their nest in the attic and the colony kept growing. Well we don't really mind them, host wanted to leave them alone but they were pestering the neighbors so we eventually had to poison the poor wasps with permethrin. Shit works, all ded now.

I wish we had hornets again, they're cool! Had a nest in the attic for 3 consecutive years but then they didn't come again. They eat wasps and a lot of other insects and are very docile compared to wasps or bees.