Just had this problem myself. Was out cutting at the log pile and noticed a bunch of bees. Finally located their nest attached to the bottom of one of the logs. Sprayed it and knocked it down without getting stung. Very next day out cutting again, cut through a log, chunk falls to the ground and bust open. Bees come out everywhere all pissed off....apparently there was a nest in the hollow core of this log. Some how I escaped without getting stung again!