> >Suppose I feed my bees say 20lbs of sugar syrup, what weight of consumable
> >stores end up in the combs as the result of such feeding?
> I should have added that the syrup is 2:1 ie 2 kilos of sugar to 1 litre (1
> kilo) of water.

That's the mix we use for fall feeding.  Spring too, for that matter.

How much weight gain can you expect from a given amount of feed?  That's a
million dollar question.  There are theoretical answers, but I doubt anyone will
ever answer the question definitively for all practical situations, since there
are so many complex factors involved when bees are not kept isolated from the
environment.  Having said that, I'll try to sketch in the factors involved so an
educated guess may be possible:

At this time of year, there are normal daily weight losses taking place in hives
up at our latitudes.  Old bees are dying off, stores are being condensed and the
final capping is taking place.  If the hives were nicely settled down and
semi-dormant before the feeding starts, then the metabolism of the hive is
increased by the stimulation of the feed.  Bees will become active to deal with
the opportunity, and the hive's background daily metabolic weight loss will ramp
up to a higher plateau for the duration of the feeding.  This results in
accelerated weight *loss* for the duration of the stimulation (feeding) and a
for a while thereafter.

At minimum, fall feeding must be sufficiently heavy to pay back this more or
less fixed cost.  Only after that is accomplished, do the hives begin to gain
weight that will stay with them after the feeding period.  Remember: spring
stimulative feeding deliberately ramps up the hive metabolism and encourages
brood rearing and foraging by providing small dilute amounts from time to time.
This is the opposite of what we want to do in the fall.  If a small amount is
fed (a gallon or less), the feed may actually not raise the weight of the hive
much, if at all, and brood rearing may resume or increase, actually negating the
weight gain from the feeding, consuming stored pollen, and wearing out the bees.

On the other hand,  if large amount is fed quickly, then it will be usually
stored fairly efficiently.  There are naturally, some losses associated with the
effort of converting to invert sugars, the energy consumed in warming the feed
and transporting it, and in evaporation of the water component.  Ambient
temperatures and humidity will have an effect on this, as will the condition of
the hive and the combs which are to be filled, and the location, the temperature
and the concentration of the sugar syrup fed.

The gains that arise directly from the feeding alone are hard to isolate.  Bees
are often flying around looking for things on a nice day, even when the hives
are settled, or partially settled for the season.  Sometimes there may be a
potential or actual light flow available which will complicate any effort to
evaluate the gains from feeding; the stimulation of feeding may draw them away
from the alternate (free) source, or conversely stimulate them to discover it or
to exploit it more fully.

On top of that, feeding may cause some robbing of your hives by neighbouring
bees or vice versa, further complicating the measurement.  Some types of bees
may be stimulated to fly much farther than others by feeding activities, and may
lose more of their populations due to fighting or other factors.  Diseases such
as nosema will affect the ability of the bees to utilize syrup provided.

We have always intended to weigh two yards, feed one a measured amount of feed
leaving the other unfed, and then calculate the weight gain/loss in each.  I
doubt that the results would be conclusive, and I think I would have to repeat
it many times and take an average.  I have always felt in many of the
experiments that I have run, sometimes involving thousands of hives, that the
effect of outside factors is often larger than the effect I am attempting to
measure.  No matter what I do, and how many hives I use in a test, I cannot get
the neat tabulated results that the researchers do using only a few hives.
Never could figure that one out.

Anyhow, all in all, in my experience, when hives are fed all the 67% sugar syrup
they will take in a short period of time, we figure the weight gain will be
roughly equal to the sugar content of the feed.  That allows about 15 to 20%
energy consumption in the storage and conversion.  However we find that when 40
hives share 500 pounds of feed or less, we are lucky if they stay the same
weight and don't lose, so be aware that feeding significantly lesser amounts
than a gallon may not accomplish any gain, and may actually result in overall
weight loss.

allen

Thanks to all who wished me a happy birthday :)
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