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Bees & Beekeeping: Present & Past

How to Identify Colonies Robbing Hives Away from Their Apiaries

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

In the previous article, we observed robber bees hunting en masse for colonies that cannot protect their honey. The emphasis was on the hive being robbed, which is easily identified given the rush of bees into the hive, along with fighting between the hive and robber bees.

This article shows a detailed series of technical photographs revealing robber colonies, the colonies doing the robbing, and of critical importance, when the colony being the robbed is not in the apiary. The colony being robbed was well away (over 100 yds) from the apiary. (The 100-yd distance is just a rough estimate of where the round dance should have changed to the waggle dance. Researchers have long known that distance varies with Apis mellifera subspecies and their hybrids.)

Returning from far off, not every forager dances, unless she has found an exceptionally good resource. A robber bee returning loaded full with pure honey, easily acquired, in a summer dearth, will definitely dance. The robber bee would communicate this ultra-rich far-off resource to nestmates by excited waggle dances, which convey distance and direction. The newly recruited bees fly away from the apiary using the location information and scent acquired from the robber bee, presumably like they would from a forager with a flower scent. (Remember, in an intense spring nectar flow, a forager bee would ignore honeycomb set out in front of her hive. The comb full of thick, completely cured honey would not matter to the bee. She would rather fly far away, laboriously collecting thin nectar.)

It seems reasonable to infer the robber bees used a waggle dance because potential robber bees were not testing and harassing the guard bees at the entrances of the other hives in the apiary. Potential robber bees would have been called by round dances conveying little or no directional information. Excited recruits would have searched locally, the apiary and the nearby vicinity, guided by scents obtained from the robber bees. In fact, the potential robbers were strangely absent, the polar opposite of the previous article.

I have observed this robber colony behavior several times but never could acquire a full set of decent photographs. Then just after I submitted the previous article on mass robbing from the usual perspective of the colony being robbed, good fortune struck, at least for educating other beekeepers with rigorous methods to identify the robber colony behavior. And just as important, we learn how not to confuse or misidentify robber colony behavior with other similar behaviors seen at the hive entrance: groups of bees taking orientation flights, the hive itself being robbed by other bees, or the initial events of a more protracted usurpation (takeover) of a colony displaying questionable behavior by a foreign swarm.

This episode began during a routine morning check of my main research apiary under a solid cloud deck producing diffuse light (no harsh shadows). The colonies were typically quiet, except for one on the end of a row. The colony causing the concern was not a large one, just a new split from the spring (see Figure 1). The bees foraged excitedly, definitely with more zeal than needed for bringing in water during the slightly cool and humid conditions.

Here is how the unusual bee behavior could be easily misinterpreted. Bees from the hive seemed to be confronting other bees. These apparently hostile confrontations occurred not only on the alighting board (see Figure 2), they extended out in front of the hive, and even occurred under the hive (see Figures 3 and 4). It seemed like bees from some unknown hive must be robbing this colony.

Closer, more discerning observations of the bees showed that aggression was mostly absent. The robber bees were returning to their colony with honey. Their abdomens bulged full of honey plundered from some distant hive. More telling though, upon leaving the apiary, the foragers from the end hive flew up through a gap in the leaf canopy. Their outbound flight did not remain near the ground in a direction to their well-known nearby water source (see Figure 5). The next hive had bees crowded over the alighting board and spilling onto the hive support (see Figure 6). To understand what was occurring at the end hive, we need a brief digression into some important biology.

In honey bee foraging mechanics, either for nectar or water, the older forager bees unload their crop contents to younger hive bees. Briefer unloading times convey higher colony demand to the forager bees for what they have collected –– and for them to collect more. Conversely, a longer unloading time, where the forager spends more time finding a hive bee to take her load, “tells” the forager to slow or stop collecting that material. Therefore, the younger hive bees, more intimate with the immediate needs of the colony, deploy and direct the older forager bees, which have a better perception of the topography around the hive.

Normally the hive bees unload foragers in the brood nest, obviously well out of sight of casual observations from outside of the hive, except in this situation. It would seem that the colony’s demand for thick honey (not nectar) is so high in the dearth that some of the hive bees move from the brood nest, and come outside to meet the arriving robber bees, apparently saving them the time of entering the hive. (I still need to verify that to make sure the unloaded robber bees launch from there and go back to the robbed colony. While that seems so obvious, why check, one may wonder? Human explanatory conceptions can be too simplistic. For example, historically, some beekeepers thought the foraging bees put nectar directly in the honey cells. While intuitively that seems true, an efficiency of honey bee foraging, it is wrong. Honey bee social foraging is more complicated and designed to optimize nectar collection of various sugar concentrations from different locations in the most efficient manner.)

After meeting a robber bee outside of the hive, another way to rapidly unload her becomes evident. Not just one hive bee unloads a returning robber bee, but two, three, even four of these eager bees crowd around, all their tongues protruding. The tips of their tongues touch in the honey held between mandibles of the robber bee. Demand for honey in a dearth would be intense, reminiscent of the high demand for water to cool the hive during blistering-hot summer heat.

Some technical comments. When one bee feeds another, or here where one bee unloads her crop contents to another, she regurgitates the liquid from her crop and holds it between her partly open mandibles (jaws). The receiving bee extends her tongue, putting its tip in the liquid and pumping it into her crop (see Figure 7). In the photographs, the bees with their long tongues extended are the receiving bees. Usually in a crowd of bees, only the base of the extended tongue is seen. It appears reddish and glossy. The receiving bee tilts its head so the mouth parts project forward. Sometimes it is evident that a pair of bees is sharing food, or here one bee is being unloaded. However, their different roles and the flow of resources might be uncertain, hidden in among a crowd of other bees.

If the thoracic plumose hair on one bee is substantially damp, stuck together, or matted together, that bee was probably the one returned from the robbed hive, hence the robber bee. Be aware, however, hive bees unloading robber bees in a crowd of sticky bees can become somewhat disheveled, their plumose hairs sticking together. Conversely, robber bees may not always have sticky and clumped-together hair, particularly if they have just begun flying to the unprotected honey. This method of distinguishing membership to one of the two groups of bees by their thoracic hair appearance is useful, but it might not always be definitive.

On the alighting board of the end hive, Figure 8 shows a robber bee being unloaded by three hive bees. The antennae of the bees involved in the transfer are in rapid contact, telling the observer where the bees are directing their attention. Now the aggravated bee behavior on the alighting board (from Figure 2) is better explained mostly by excited unloading of honey-laden bees in a dearth (see Figure 9).

So far the known honey-bee foraging theory and experimental results can account for what has been observed, except for perhaps the definitive hallmark symptom of the next condition. First appreciate that the returning robber bees have been in a foreign hive. They have searched frantically through it, alongside hundreds of other bees in the hot, humid stickiness of that hive during the summer heat. Excited bees have chewed open the honey caps, gnawed down the cell walls, and tracked sticky ooze over the combs. Back at their hive, when the robber bees hold still while being unloaded, the hive bees will sometimes begin licking them. Why? The sweet stickiness covers them. The small clumps of bees scattered about in front of the hive comprised …