By coincidence, a respected NZ beekeeper posted the following on
our Nat'l Beek Assoc list just after I raised the q on Bee-L:


I have an observation , accurate I hope, some others out there may have a
comment on.
Recently I have moved a lot of very hungry hives off bush sites on the Otago
coast after a mostly failed attempt to get some Manuka honey.  Just too
much cool
and damp easterly weather when it mattered.
I have moved them inland where at higher altitudes there is still some
fields of good clover left.  Existing hives in the area have made a fair crop
considering the season, but they have now effectually stopped.  Getting a few
boxes of cut comb finished looks unlikely and they are robbing  soon as I am
in the yard.( And unusually agressive too.)
However, and here is the point,  the very hungry hives, now in just brood
chambers, have really very quickly pulled in their winter stores.  ( I'd say
on average about 10+ kg in two weeks).  Same pastures and weather, but
apparently much more "desperate" to be anthropomorphic, to collect honey.
This is not very scientific, nothing weighed for example, but certainly
seems to be happening.
I know from past experience if I were to harvest all the honey off the
established colonies now and put a freshly extracted sticky on, then they
would be more likely to work the tail end of the season and maybe even make
me another box.  I understand this is a result of chemicals released from the
wet?
 So do bees actually " decide" how hard they will go out and gather on the
basis of how much stores they have?  Do they " know" how much honey
they have stored for winter?  How?  Is there a chemical stimulus involved ?
Or am I just fooled here and the other hives have put their 10 kg in the
brood nest too?
All theories welcome.