Over the last few nights I've been particularly aware of a louder than usual humming coming from one of my hives - the larger and hotter of the 2. I just reaaranged that hive for winter and have internal pail feeders on both hives. I didn't really notice it during the day but it is quite loud at night now. I have only a small cleated down bottom entrance open at the moment and the bees visible around it are fanning vigourously -an amazing stream of air is coming out...
There was some robbing a few days ago but that has fallen off. I did observe at least one queen in that hive - the loud one - 2 weeks ago along with lots of larva and capped brood. On monday, when I re-structured that hive, I did see plenty of capped brood but didnt see any larva or eggs or a queen. The bees were extremely angry so I wasn't able to observe as acutely as I normally would have. Possibly queenless?
Happy bees hum while working. The old "Whistle while you work" routine. In this case they are humming while dehydrating the syrup into honey.
Brian hit the nail on the head.
Don't know about MD, but here in NY we are actually getting a fall flow the last week or so and they are busy all night drying nectar
We are having what I assume could be described as a respectable flow here too. What's interesting is that my smaller hive makes almost no noise at all during the night; if I press my ear against the brood box I can hear a gentle hum but nothing when standing in front of it. No detectable airflow coming from the entrance either. Are these differences simply attributable to the diffrences in population size?
Could be size, could be genetics. Some hives are harder workers than others.
What does the hum sound like? Dissonant? Harmonious? A loud dissonant roar is usually an indication of either robbing or queenlessness. A loud harmonious roar doesn't necesarrily mean anything. Especially if it's just temprorary.
If I had to choose I'd say harmonious. They are also very touchy, even in the dark. I bumped into the hive at one point last night and the very loud hum jolted into an instant, brief roar. In a flashlight beam I can see 15 to 20 bees just outside the opening (about a 3" slot) fanning in unison.
The guard bees plus the quick interrupt in the harmonious hum means that they have been repulsing robbers. Either that or they are the robbers chortling over their loot. Check the weaker hive to verify and feed if necessary. If robbing is happening to the weaker hive reduce the entrance to just a couple of inches.
Brian
Would robbers linger overnight in a hive they've robbed. I am fairly confident that this hive did repulse the main wave of robbers as it was/is quite strong and I was able to reduce the entrance fairly quickly.
I suspect the weaker hive is ok too; I noticed an occasional robber today near the small entrance hole - every few minutes I'd see a couple of bees wrestling in front of the hive. But it was nowhere near the frenzy that I observed on Sunday.
The fact that you see a few bees wrestling shows that it's been robbed recently. I don't think that a robber bee would stay in the hive overnight as any bee not from the hive not arriving with nectar or pollen would be attacked. But there is always the possibility that the guard bees were overwhelmed (which is how robbing takes place) and a few stayed behind due to time of day.