Last night, when we were preparing bees for
winter, my wife started to wonder, what was the
sound she did hear every now and then.
She described it as wild and like a kittens scream
for her mother. She did hear it during a long
time, more than half an hour. I did  hear it a
couple of times, and it was very small sound not
like beeb but like screetch or like a beeb with
varying tones.
The length of the sound was about 1 - 1,5  seconds
and the interwalls between piping varied from tens
of seconds to minutes.
She has a green beesuit, and there was about 15
bees under her collar just near her ear and one
(?) of them did make the sound.  At that time the
night was just darkening and we could not identify
individual bees.
Maybe it was the sound of a queen, a flying one,
because otherwise it could not have been on the
beesuit so high up.
The evening was warm, about 24 centigrades, no
wind, no clouds.
Swarming time is here over now. We inspected two
hives at this time, and both of them had plenty of
room. At least the second hive had a queen cell,
but this piping bee came probably from the first
hive.

Kauko Kangas, beehaver for five years
Nummi-Pusula (near Helsinki)
southern Finland, Europe