Grumps is right. We had a nest......here's the story.....
apc got bitten by something, went nasty (blood poisoning etc) found out at horsepickle that it was a spider. The following day I found said spider in our bed. Beasty thing that it was. This we later discovered was the baby.
Two days later I heard a lot of effing n blinding from the bathroom, seems apc found mummy spider, (covering the entire top of a full loo roll)
Following this He discovered DADDY. apparently I don't want to know or I will leave the island but I'm sure I heard him crying in fear one night.
We then found the nest.
webs so thick they were like pillow cases.
regarding your problem, if there are 3 on the ceiling, the rest are making babies and lying in wait.
Sleep well