Trying to figure this out...

[bassman1977]

Here's the scenario...

Time:  5:30pm
Temp: about 55 F
Hives status:  All quiet few coming and going.

Put some syrup into a few hives that were low on honey (this wasn't too great of a year for goldenrod...effects last years drought perhaps?)  All hives in the yard remain quiet (yes there are plenty of bees in the hives).  Went to put some mouse guards on 3 of the hives I didn't get a chance to install.  Hives still quiet.  Went to final hive for final mouse guard installation (all of the hives fed received a mouse guard today).  A few bees start to congregate...I believe they came from inside this hive.  Suddenly more and more.  By the time it was said and done there were between 30 and 40 bees coming and going from this hive.  Some where in a pissy mood.  The other hives remained cool, calm, and collect.

What happened here?  My thoughts are:

1.  I triggered their alarm pheromone when I either fed them or installed the mouse guard
2.  Bees coming home from foraging (I wasn't in their flight path installing the mouse guard).

This is my one hive that was generally more aggressive than the others so I'm thinking #1 is more likely what happened.

I'm interested in some other thoughts.

[Michael Bush]

Smoke tends to keep things more controlled.  Without it you get alarm pheromone going and you get a mass reaction.  With it, you tend to only get a few excited.  That's what alarm pheromone is for and what the guard bees are supposed to do.  Raise the alarm.

[Understudy]

Some bees are nicer than others. And will tolerate more disturbances than others. You dealt with one that has a low tolerance. Those are bees that I respect because they can be harsh, but they tend to survive.

Sincerely,
Brendhan

[KONASDAD]

It weas too close too dusk. Its almost dark here at 5:30 if there any any clouds.

[bassman1977]

It weas too close too dusk. Its almost dark here at 5:30 if there any any clouds.

I thought about that too but because the other hives were ok, I didn't think that was it.  I think each suggestion mentioned may have had a hand in their reaction.