I have observed many queens piping.  They stand still on the comb face,
flatten their thorax and abdomen against the comb, extend their head and
mouth parts forward, and appear to pump their abdomen to make the noise
(actually much like a cow or lion bellowing).  When finished they stand up
again and move on.  They may stop several times exhibiting the same
behavior.  I've never seen or known workers to pipe but have found it takes
some practice to tune one's ears to determine the exact location of the
piping, I think because the sound is so piercing the ear doesn't easily
discriminate the distance to the source.  I can now usually go to the one
or two frames in the immediate vicinity of the virgin queen.
 
James C. Bach
Yakima WA
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