The Beekeeper’s Companion Since 1861
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Bees & Beekeeping: Present & Past

Bees Robbing Honey en masse and How to Avoid It

- September 1, 2023 - Wyatt A. Mangum - (excerpt)

On numerous beekeeping projects, I have traveled to various countries helping beekeepers with their problems. These assignments required working with different strains and species of honey bees. In Bolivia, I worked with Africanized bees, and yes, they lived up to their defensive reputation. On the other hand, an elderly beekeeper and I could inspect his (single story) hives without gloves. The bees aggressively hovered and followed our every hand movement, ready to pounce. The bees did sting us, but not much.

Working among beekeepers in Asia, it is best knowing the life histories of their multiple native honey bee species, at least the main ones: the Eastern honey bee (Apis cerana, the sister species to Apis mellifera, our Western honey bee); the Dwarf honey bee (Apis florea); and the Giant or Rock honey bee (Apis dorsata). In India and Bangladesh, I worked on several assignments with Apis mellifera, which is not native there and had been imported years ago. The stock I encountered over both countries was a pretty orange Italian bee and incredibly gentle. I have been with commercial beekeepers just after unloading big truckloads of hives, and nobody had a lit smoker. Arriving at an apiary of 100 hives, bees flooding into the sky, my beekeeping hosts, some ten or more, troop off into the hum, hardly a thought of smoke, a huge contrast to Africanized bees.

The new beekeepers I met mostly wanted Italian bees because of their higher honey production compared to their native honey bees. (Early on, some beekeepers do not fully understand the full cost of the nonnative Italian bees, feeding them, problems with tropilaelaps mites, etc.) I inspected small apiaries of Italian bees (or A. cerana) in different rural villages. (These small apiaries seemed like those of hobbyist beekeepers. Really the hives were important components of family wealth, not only in honey production, but in the value of the hives themselves, helping to protect the family from falling into financial ruin when faced with a large sudden debt.) On these trips, I listened a great deal and heard all sorts of surprising things.

One beekeeper, a polite but proud young man, had built up an operation of 20 Italian colonies. He told me once that they required considerable feeding during a dearth. For feeding small amounts of syrup (a cup or two), the typical way was to partly fill a thin plastic bag. After tying off the top and pricking the bag so it leaked slowly, the bees came up from the frames to find the sweet.

My beekeeper friend tried a different method. On each hive, he placed a shallow pan and filled it with syrup. He explained he thought the bees would fly up from their hives to only the pan on their hive and sip the syrup. After drinking themselves full, the bees would fly back down to their entrances and deliver the sweet loads to their colonies. Then the bees would fly up to their pan for another load, and so on. He imagined all his colonies feeding contently together, politely, idyllically, such a lovely scene. I listened, a poker-face smile plastered on me, seeing an orange bee explosion, something like Figure 1.

Mass robbing. Here is a working definition: During a dearth of nectar, bees from one or more hives rush into a hive whose guard bees are not numerous enough to withstand them. Rapidly, the robber bees remove the honey from the hive.

After the spring nectar flow, mass robbing is expected when a colony’s defense breaks down because of a reduction or disruption in the number of guard bees. If a colony dies in the summer, obviously its honey is completely unprotected. Robber bees from the other colonies typically rush in to remove its honey. More often I see a weak but failing colony able to maintain guards for a time until bees from other colonies manage to evade them before overcoming them (which gives time for corrective action).

The cause of colony death, preceding mass robbing, need not be exotic or complicated. Varroa mite populations becoming too large or failing queens are common causes. Moreover, roughly a month after the conclusion of the spring nectar flow, I see robber bees overpower some colonies. These were strong colonies earlier in the season, which swarmed. The daughter queens failed to mate. And now, the dwindling colony populations are weak enough to succumb to robbing pressure. Hence my management rule: Confirm laying queens in all colonies soon after swarm season. In locations where small hive beetles are prevalent, the beetles commonly begin destroying the honeycombs, limiting the amount of honey remaining for the robber bees. The loss is a colony and its drawn comb.

As successful robber bees return to their colonies, they rapidly recruit additional bees to search for the unprotected honey. When I see this excited dancing in my observation hives, it appears as a sloppy round dance, a dance that conveys little or no directional information. The recruited bees leave the hive searching in all directions. These searching bees are heavily influenced by comb or honey scent, an important point in controlling or trying to stop the robbing, as we will see. Appreciate though how “irrational” and unexpected this “crazed” searching seems. Figures 2 and 3 show mass robbing flight. Figures 4 and 5 show two spatial scales to understand the bee density in the air.

Bees that have not yet located the dead colony, and learned a quick flight path to it, search within and near the apiary. For a suburban apiary carefully concealed in the backyard, keeping a low profile, excited bees searching invasively into neighboring properties alert most people to the bees, calling for an explanation from the beekeeper. Obviously, having the neighbors learn of the bees by meeting them in robbing mode is far from ideal.

Here is where I confess about the two “hives” in Figures 2-5. It was in April, during a dearth before the main spring nectar flow. The bees found a few honey frames I had removed from a hive and began robbing. Those two hives were just empty bait hives, each containing a pair of empty combs, nothing more. The bait hives were on the ladder where I assembled them. Now imagine those hives as a small box with some waxy scent in it, on your neighbor’s favorite porch. It does not matter that the crazed robber bees were doomed to fail, it only matters to a scared person that the bees “took over” the porch and that their safe place will always be less safe.

Robber bees searching for a honey source exhibit a characteristic weaving flight close to the ground. The bees will even search stored hive equipment like my frames in hive bodies without comb, only woodenware. Under normal dearth conditions, normal water foraging (near the house) and drone flight in the afternoon from my main research apiary (behind the house) has a typical “spatial hum,” hum locations in space. But just leaving the back door and hearing the hum in different places, over in the stored equipment or on my work bench, tells me something is wrong. One possibility is robber bees searching for an overpowered colony somewhere nearby. The hum is “wrong,” not in its normal locations, or too loud, too excited for mundane water hauling.

As more bees excitedly participate in robbing, additional guard bees appear at the entrances of their colonies. Unprotected honey in a summer dearth causes a tumultuous response similar to the response shown in Figure 1. Those bees were wildly hunting sugar syrup in a summer dearth. If they were searching for honey, I would expect them to overpower five-frame nucs, even strong ones with small entrances. All mating nucs would be robbed out because they are even smaller colonies. The robbed-out nucs could still have queenright colonies in them, although weakened. For their recovery, any syrup feeding or stored syrup in the nucs would incite additional robbing to the point where the nucs could not contain syrup. One group of hives, either the robbing colonies or the nucs, would need to be moved away farther than the foraging range of the apiary. Usually I move any salvable nucs because sometimes I cannot identify all the robbing colonies.

During times of nectar poverty, a disruption in the number of guard bees can happen when a beekeeper inspects a hive. During the inspection, the supers were set aside, exposing the combs or honey in the broken burr comb. Bees just passing by quickly orient to the flood of honey scent in the air. Some will acquire the sweet, return to their hives, and inform others of the rich food source in a time of starvation. The beekeeper may not notice the robbing until numerous bees are robbing and fighting. By this time other robber bees may have returned to their hives, which could be only several feet away, to dance the astounding news of an incredibly sweet food source, when the foraging threshold is already extremely low.

As I examine a colony under dearth conditions when robbing is quite likely, I constantly watch for the first few bees harassing or fighting with the bees of the exposed colony. Again, but with many fewer bees, their hum is out of place. No whiny buzzing should be near the set-off supers. Often, I hear the curious searching bees before I see them.

When conditions are favorable for robbing, keep colony inspections brief. For frame hives, cover exposed supers with extra covers. In my rural apiaries, I also use towels. They are easy to pack, have other uses, and are standard equipment on my bee truck. For stacked supers across the rim of an upside-down telescoping cover, watch for robber bees flying up under the lowest super.

For top-bar hives, the top bars are in full contact, which limits robber bee access to exposed combs. Usually though, the beekeeper removes the first few top-bar combs and places them in a …