Summer 2015 in the Hamilton area was the worst I've seen for yellow jackets and by mid-August they were nesting everywhere. After seeing quite a few around my front door I stood still and watched for a bit. Within a minute, I spotted a steady stream of them landing at the top of the brick face and entering under the siding about 12 feet from ground level. I tried a can of wasp spray while standing on a ladder about 8 feet away. After a brief pause with a large swarm around the opening, they started landing and entering again. I tried again twice with the same outcome.
So I called EMBO and made an appointment for two days later. The service person was punctual, courteous and completed an application of powder within a few minutes. He explained that the powder was more effective than the spray I'd tried because the insects track it into the nest and poison the others. He also explained that a heavy rain too soon after the treatment could wash the powder away and a second application might be required.
It didn't rain and within two days, there were no more wasps returning to the opening. I called to say thanks.