Subject: Why do groups of yellowjacket wasps remain motionless outside of their nest

I have a yellowjacket wasp hive inside the overhang above my balcony. There are 
a openings in the overhang that I believe are access areas to the hive within. 
Around or near a couple of these openings, a group of about eight or so wasps 
sit motionless, only rarely moving or grooming. Ocassionally, a slightly larger 
(older?) wasp will fly into the midst of this group. The arriving wasp excites 
the once motionless wasps. There appears to be an  exchange between the wasps 
involving what appears to be wrestling, head-to-head butting, and general 
commotion. It seems like the new wasp isn't an intruder, but maybe a feeding 
parent or messenger of some sort. When the older wasp leaves, the commotion 
stops and the wasps return to their motionless state. What's going on here?

Re: Why do groups of yellowjacket wasps remain motionless outside of their nest