Hi to both George and Tom:

Ok, George is correct about being able to predict for individual bees.
However, we addressed this issue in some of our models, and the following
does seem to work.

Our models make reasonable (parallels real colonies in real field settings)
if we use weather as an important driving variable.  A lot of work was done
on bee longevity in Europe.  Marked bees were flown to feeders, both in
outdoor and indoor settings.

The bees all displayed a similar pattern.  The longevity of a healthy bee
seemed to be a function of the distance flown.  I'd have to dig up my notes
for the exact distance.  After using up its alloted flight life (flew more
than the distance limit), the bee dies.

Now, you can look at it another way and estimate the number of trips and
distances per trip.  As I remember, we used 10-12 flight days as the
average time that it took to add up to the flight distance limit.  We then
went to the literature and found that this number appears in several
studies (many of which did not appear to be aware of the European studies).

Ok, so if the weather is nice and food resources are available, we can
expect our typical bee to live 10-12 days.  If the weather is variable, the
bee will live for a longer period (flies some days and not others).  In the
winter in northern climates, the bees don't forage, don't add up flight
distance, and as such live forever (or at least until they start flying in
the spring).  Now that's what the model thinks.  Any beekeeper knows that
some die in the winter from old age, stress, nutritional shortfalls, mites,
etc.

But, for a healthy colony, the model fits better than one might expect.  We
can get reasonable approximations of population size for any time of the
year by plugging in the general weather conditions for the area.

So, George's Dec 1 bee will live a lot longer in the north, but not as long
in the south as the July 1 bee.

Cheers