glen, most of the time the bees will take care of them if they don't have big entrance or holes to defend. this year, they were so relentless that the took down even my strongest hive....and, as i said, it was partly my fault for not being able to stay on top of the traps and stuff...although, bad as they were, it might not have mattered....
you know how it is when you walk through clover and there are bees all over the place? that's how thick the yj's were. they were everywhere.