The ones here are an artificially-introduced breed which doesn't eat aphids. They congregate on the windows outside the house and crawl in continuously. I've had days where I've had to kill several dozen in my room alone; and when they die they give off this horrible smell. For a while there were even more on the skylight--had to use a vacuum extension to get rid of them. That helped, but they still come in through the windows, maybe a dozen a day now.