I don't believe that it is the engine that irritates them. My experience
is different from Ted Fischer's in that my bee blower is seldom of much
interest to the bees. It seems that they are irritated more by the cutting
blades close to the hive entrances. I tried a hand operated
clipper near the entrances and they stung me and it repeatedly.

My solution to the problem is to cut the grass near the hives with an
antique scythe. Another one is to put down rolled roofing on the ground
in front of the entrances. They don't seem to mind power machinery if it
is more than 5 or 6 feet away.

Best regards,

Donald Aitken
Edmonton Alberta Canada