About 10years ago I called in a professional exterminator as we had a low sloping tiled roof with a wasps nest underneath. He clad himself up and informed me he was going to spray white powder under the eaves. He said they get quite angry when sprayed and ,in the trade, they call them Ghosts as they re buzzing around furiously in their new coat of white. I was advised to ensure all the windows and doors were shut before he sprayed. I came to the window and gave him the thumbs up for the 'go ahead'. Next thing I saw was the lance quickly extracted and him being chased by the angry swarm down the front path. I was amazed to see him rip of his hood ,jump in his van and drive off..I had to ring him up 3 days later and remind him to collect his fee.