In eastern Virginia, after a mild December this past year (2021), the temperatures crept up to a mild 63°F in the afternoon. It was just barely into the New Year, on January 2, 2022. My bees flew into the leafless woods all around. They returned with just a trickle of pollen (the loads in white and orange). While not much, that welcomed timing was long before maple pollen (pollen loads in greenish yellow) expected later on in early spring.
With snow and cold predicted for the next day and the climate models showing January unleashing its typical misery of cold, I conducted some of my winter brood nest inspections. Figure 1 shows how I opened a top-bar hive on a warm winter afternoon with minimal disturbance to see the brood nest. Most prominently (for early January), the brood nest consisted of the capped brood shown in Figure 2. A patch of larval brood almost the size of the capped brood was on an adjacent comb, all in worker brood.
This amount of brood is expected for about the end of the year in my location, although the brood nest size does vary in size among the colonies. I keep these brood nest inspections brief, and I rarely do them on my frame hives because of the excessive bee disturbance. While the amount of brood was typical, this colony had a large adult population, easily protecting the brood in the coming cold.
The next day a branch-bending, tree-snapping, heavy wet snow covered the land (see Figure 3). A bitterly cold northwest wind stomped the temperature down to 15°F at my home apiary (by the morning of January 3, cold for this area). The snow froze solid by the next morning.
I have research hives that I check daily, including all through the winter. Between bouts of data collection, I mostly confirm the bees have not been disturbed, which is more of a concern with snow, ice storms, and wind storms too (and the emerging threat of bears). Factored in with the damage from the weather is another threat known since having 200 top-bar hives scattered on farms for pollination over a couple of counties in North Carolina.
Within their striking distances, I am keenly aware of all trees leaning toward my apiaries, including the bee house. While in past storms, I have had some terrible times with trees falling on my bee house and hives, I was spared this past round of wet snow. I returned to a more tranquil winter beekeeping like I have been developing over the past several years.
On cold winter nights, I patrol through my apiaries recording thermal camera readings of the colonies (see Figure 4). I can discern various colony conditions, more so for the top-bar hives because the cluster heat only goes through the hive body (one wall). With frame hives, the end bars essentially form a second wall, absorbing the heat and blurring the image. Even still, I can tell the colonies that have perished (seen as a cold blue hive). Although more difficult, I can tell some hives have small clusters putting out a weak amount of heat. I can also tell some colonies are becoming weaker over several weeks in the winter, producing less heat, indicating a dwindling bee cluster.
Later in the spring, knowing the vacated hive equipment allows me to inspect it first, and have it ready for possible use elsewhere in the apiary (like moving frames of honey to redistribute food among hives). I can also tell the vertical positions of the clusters in the (frame) hives, tipping me off in advance to clusters needing their hive bodies reversed (see Figure 5). The thermal readings also provide advanced warning for not reversing hive bodies, when that might leave the cluster broken apart.
Without a thermal camera, one can still do all the spring bee management like before the technology became available. A beekeeper can do a good job at finding weak and dead colonies first by perceptive bee watching, and sometimes without bee flight, say on a cold day after the bees have flown for several days.
For example, I can tell the colony in Figure 6 has perished, even on a cold spring morning without any bee flight in the apiary. The little critical detail is at the upper entrance (see Figure 7). The sticky material was apparently “tracked out” of the entrance by robber bees. This material can appear at the lower (reduced winter) entrance too, again apparently when robber bees use that entrance for an exit.
Furthermore, if the bees are flying in early spring, be careful not to think the colony in Hive 40 is alive when it has perished. Spring robbing is rarely like its summer counterpart occurring in a dearth, notorious for having large bee populations exploding in mass riots over even small amounts of spilled honey (called mass robbing). Early spring robbing usually consists of a low number of bees slowly and diligently working to remove honey, including uncapping it in a cold hive. These few dozen or so robber bees are restricted to work during fairly brief periods when the days (sometimes just afternoons) are warm enough to support their round trips to “forage” at unprotected combs (usually at restricted uncapping sites, which we will see in Figure 8).
From the hive entrance, seeing heavily loaded bees leave the hive while empty bees return is suspicious evidence for robbing (in general). Specifically, that would be bees with large abdomens leaving and small abdomens entering the entrance. The abdominal size difference is more than expected from defecation (cleansing) flights after several days of flying when that difference should decrease and when the warm flying days allow robbing to start.
When in doubt about the suspicious bee flight, I compare it to the concurrent bee flight from other colonies in the apiary. The suspicious bee flight may have greater than or less than the number of coming and going from the entrance compared to the typical bee flight from other colonies. Therefore, the numerical strength of the suspicious bee flight is not too helpful. Look then at the type of bees in the traffic at the entrance. I expect the suspicious bee flight to lack pollen foragers, and possibly lack drones if later in the spring and past weather conditions that favor drone production in the other colonies.
(I have seen rare cases where spring robber bees and pollen foragers flew from the same entrance, but this occurrence should now be known as progressive robbing, where here the (weak) colony’s hive bees cannot detect the foreign robber bees. Also possible, the robber bees could encounter essentially no guard bees at the entrance, and they manage to easily evade the hive bees from the weak cluster. The robber bees remove honey from unoccupied combs well away from any hive bees, mainly by evasion rather than by “acceptance” by the hive bees. To my knowledge, this evasive robbing is not called by a formal term.)
In short, bee flight in early spring does not always indicate colony survival because from some hives the flight could be robber bees. Also misleading can be the colony doing the robbing, depending on the amount of honey it acquires and perhaps on the duration of the robbing. From the colony being robbed, I try to flight-track the robber bees back to their home colony (the one sending them).
That procedure is a routine part of my beekeeping practice for spring robbing or summer robbing, whether it is mass or progressive robbing. Here is an important point. No matter if the suspected robbing might involve full-size colonies, splits, nucs, mating nucs, or even new package-bee colonies, not for one moment do I think the robber colony must be a big strong colony. Some of the most cryptic, chronic, hard-to-spot progressive robber bee flight has been between new package-bee colonies.
Once I found a couple dozen devoted robber bees flying a low return flight from a robbed package-bee hive. They weaved back through the chaotic bee traffic in the apiary to unload their sugar syrup in another package-bee hive. Their colony grew quickly, gaining weight remarkably fast, almost too fast, compared to the other package-bee colonies. (In general, compared to the other colonies, such colonies could be genetically better, or be healthier, or have less of a parasite load. Also through careful observations, see if such colonies are not just better at progressively robbing other colonies.)
From the colony being robbed, drop-by-drop, the robber bees dripped away the sugar wealth of the robbed colony. This hive mysteriously grew slowly and hardly gained much weight even in a mild nectar and pollen flow. It did not matter that both hives had internal frame feeders, which I routinely filled with syrup. This kind of progressive robbing, occurring later in the spring (package bee time), can still occur among package bee colonies.
Back at the apiary in the early spring, the robber bees leave fairly characteristic uncapped honeycombs after they have chewed open the caps to remove the honey. Except for uncapping the cells, comb chewing is minimal with early spring robbing. In particular, chewing down into the cell walls is barely noticeable or completely lacking.
For early spring robbing, comb damage to the cell walls is nothing like the excited mass robbing in the summer where the bees chew a third to a half of the cell walls away, sometimes even more. A mouse chewing the combs in the winter is the worst. Mice can remove the cell walls down to the midrib (foundation) of the comb or gnaw holes in the comb to make room for their nests.
The next four photographic examples originated from my in-depth day-long workshop on bee management with top-bar hives. The same bee biology and symptoms occur in my frame hive operation. In Figure 8, the comb was completely full of capped honey (both sides). The average total weight of the comb is about six pounds. From spring robbing, the bees have been slowly working across the comb, chewing open the cells and removing the honey. In a cold hive on warm afternoons, groups of robber bees typically work closely together, which would help to retain their communal heat.
The cells just above where the uncapped cells and the capped cells meet are instructional. Also note the ridge of burr comb marked RoBC and the short white arrow. On the left of the RoBC, under the red dashed curve, and above the red arrows, note the uncapped cells right above the solid area of capped comb. The uncapped cells appear partly uncapped and kind of raggedy. Here the robber bees left pieces of caps attached to the cell rims, as if they were working just enough to remove the honey. Apparently, this condition is one way spring robber bees leave capped honeycomb after removing its honey.
On the right of the RoBC, under the green dashed curve and above the green arrows, note how distinctly the capped honey cells turn into uncapped cells. The uncapped cells appear trimmed to their cell rims. Apparently, this condition is another way spring robber bees leave capped honeycomb after removing its honey.
Therefore as a general observation, beginning with capped honeycomb in a dead colony during early spring, robbing produces both …