My poor sister told me she woke up in the middle of the night and her entire bedroom was a-buzz with literally hundreds of wasps. They were all over the curtains, the walls, the furniture, and one had even stung her foot, which is what had wakened her! She's a tough lady, so she merely swatted them out as best she could, but couldn't see where they were coming from. The next night, there they were again, but in reduced numbers.
I told her to contact the Pest Control people, who would locate the nest (usually a thing like a large paper ball) and eradicate the blooming things permanently. I reckon the nest was probably in her loft.
She hasn't done this though, and today I got another e mail saying they're back again, but only about a dozen!
I'm only afraid of spiders, but wasp stings can be dodgy.