I used to have them. What a pain! When they swarm in a sunny spot, like on the side of your house, spray them with soapy water. This gets rid of them. But you have to be persistant.

Also, try to get rid of as many as possible before winter sets in, or else they overwinter in your house walls and come out en masse in the spring - often inside your house!

We get the walk-in Raid traps for them here, because they are so bad. I also squish as many as I can.