Eugene said:

> I got a swarm call...
> ...had been there since late yesterday.

So the swarm had been there long enough for scouts
to have found several choices in new colony sites.
The longer the swarm "hangs around", the more certain
you can be that scouts are dancing in favor of a new
hive location and/or the colony is coming to a consensus
about a new home.

> ...all the signs of a successful swarm collection;

Gee, I did not know that there WERE any such
signs other than "getting the bees in a box".  :)

The outcome of your attempt may force you to
reconsider your faith in "signs" of this sort.

> ...and some additional bees were entering.

Perhaps scouts and recruited "critics" returning from
visits to review and critique one or more possible
hive locations?

> ...I suddenly noticed that bees were coming out!
> So what happened? Did scout bees return with news
> of a new home site AFTER I had hived the swarm?

I'd guess that they were in the process of deciding
on a new site before you got there.  I doubt that
the entire process takes only 5-10 minutes, and
the bees had nothing better to do than find a new
home once they settled on the sign-post.

> Or were they already preparing to leave,

From what you said, I think so.

> and if so, why did they stay in the box as
> long as they did?

Well, here's the current consensus on how
swarming is supposed to work.

  Most times...
  Maybe...
  If something else doesn't happen...
  And if Mercury is not retrograde...
  Except on Tuesdays...

a)  Scouts go out to find potential sites.

b)  Findings are "reported" via dancing on the
    surface of the swarm (has anyone ever filmed this?)

c)  Bees are "recruited" by the dancer, as in foraging

d)  Those bees go check out the reported site.

e)  They come back and also dance.

f)  After enough tours by critics, a consensus is
    reached on which is the "best" site.

g)  The swarm as a whole leaves.

You apparently tried to collect a swarm that was
at least at step (d), if not (e) or (f).

Not much one can do, except not give swarms the
option of embarrassing you in this manner.

Prepare a cardboard box to hold frames, and put a
screened vent and a few cone bee escapes (pointing
inward) in a lid flap, so you can capture the swarm,
tape up the flaps, and let any "stragglers" enter via
the cone(s).  The idea here is that "no one leaves"
once you get the bulk of the swarm boxed.

  Boxes for rack mounted networking gear are
  exactly the right size for this purpose, as
  equipment racks are 19 inches wide by 24 inches
  deep, and the boxes are slighly larger.  I use
  medium frames, so a box from any Cisco 72xx
  (or larger) router is perfect.  Server boxes and
  switch boxes are also the right size.
  Ask your local network guru (every town has one
  these days) for a box from "any 5.25-inch or deeper
  rack-mount device".  The foam that is used to cushion
  the equipment can be cut with a razor blade to make
  "frame rests" recessed into the foam to keep the
  frames from banging around in transport.  I leave
  about 1/2 inch of foam between every frame ear
  cut-out to insure that the frames do not bang.
  Cut out the foam thinner than the width of the
  frame ears so friction will hold the frames still.

Cardboard boxes are also much lighter to carry, lift,
handle, and hoist on ropes to high locations.

Then, you can take the sealed swarm home, and hive
it in 3 to 4 mediums, since this is claimed to be the
approximate the size of the "ideal" cavity size
found as an average of some large number of feral
colony locations studied.

But even this does not mean that they won't take off
the moment you hive them, so I also spray the bees
with a very dilute sugar-water mix upon hiving,
just to make it harder for them to launch sorties,
or take off as a whole.  The hope here is that with
time, everyone forgets about leaving, and realizes
that "here" is a decent place.  Some open brood
stolen from another hive also helps to give them
a reason to stay "home".

But we know more about the formation of stars in gas
nebula hundreds of light years away than we know about
"swarming".  There simply are no firm "rules" for
swarming, which makes swarm collection an "art" rather
than a "science".  It is a dice roll at best.

But, if you never take chances, you never know how it
feels when they pay off.

        jim  (Who, as a child, chased rainbows with his father,
            and now chases swarms with his father, having
            almost exactly the same success rate)

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