The active beekeeping season begins in our region of the Mid-Atlantic, in Piedmont Virginia, with the prominent bloom of the red maple (see Figure 1). Maple blooms, scattered through the leafless woods, brighten up the dismal gray in streaks of red. It is a welcomed sight where I have my rural apiaries.
From thermal camera readings done during the winter, even on cold nights, I know most of the general conditions of my colonies, the ones surviving and some indication of their strengths. Now on another brief warm afternoon, returning foragers mob the entrances of the hives, eager to rush in and unload their greenish pollen pellets, the strange signature of a red maple bloom.
On a more obscure level, easily overlooked in the frantic rush of bees flying in the apiary, this early spring foraging has an almost invisible dimension. I know my bees are foraging on another source of food, one partly under my control. My bees are bringing in honey, pure honey. During this time, dead colonies, feral and managed, are probably well within foraging ranges of my apiaries. Some of my bees will likely find these sites of unprotected honey. And of course, some of those sites are my dead colonies, which have provided opportunities for observations and study (see Figure 2). As a standard practice, beekeepers should know how to identify brood diseases. For these conditions, the main one to watch for is American foulbrood, as a scale (see Figure 3).
Under my conditions, probably typical of the eastern United States, early spring robbing rarely escalates into many thousands of robber bees from virtually all colonies in an apiary fighting furiously over any exposed sweet (like we will see happens during a summer dearth; see below). Rather, the robber bees remain limited to several hundred, sometimes creeping into the low thousands. The bees seem to originate from only a limited number of hives. Strangely, while a few colonies rob honey, a concentrated sweet, neighboring colonies seem to send their foragers off for nectar, which is some 60% water. I have encountered situations when the number of robber bees remained around 50. Curious cases have even occurred for a week when the number of “robber” bees held to as few as five or six bees removing honey from a handful of sticky burr combs cut during a colony inspection. I kept the wax in an open jar, sheltered in the same apiary as the hive. (That practice is definitely not recommended because conditions could change, favoring robbing. Then irritable bees could become a nuisance to nearby neighbors.)
In the early spring when bees remove honey from a dead-colony site, they leave certain evidence indicating their activity. That evidence persists after the robber bees have finished removing the honey or when cold weather conditions interrupt their honey-removing flights. Beekeepers should be fluent in identifying this evidence. Moreover, they should be confident in understanding its implications and decisions resulting from those observations.
After repeated honey-robbing trips, back to their hives, the bees apparently track a material out of the exit hole used to leave the hive (see Figures 4 and 5), which might not be the main entrance of the hive (which should be reduced for frame hives). The tracked-out material could be off to one side of an entrance should the bees be crawling in that direction immediately before launching.
For this tracked-out material, understand the robber bees are a group of heavily loaded foreign bees repeatedly launching from the same place and direction without any hive bees to clean up any bits of material tracked from the sticky comb rims. During some several pounds of honey removal, maybe up to 10 pounds or more, bee-by-bee, drop-by-drop, launch-by-launch, the material accumulates and becomes more noticeable (see Figure 6). If the robber bees crawl over the front of the hive, they can track the material over the hive. Figure 7 shows an example, which is the front of Hive 47 from Figure 2.
Even before opening a hive, when I initially walk through the apiary, I first figure out the bee flight around me. I also search for this tracked-out material because it indicates robbing flight from a dead colony. If I see it with bee flight at the entrance, I know those are robber bees, not the normal hive bees foraging from the hive. If I am in an apiary at the same time of year, or even somewhat later in the spring, and the bees are not flying because cold weather has returned, and let’s say I don’t even know the case history of the apiary, it seems I can’t say much about these colonies, which is true. What if I see hives with robber-bee tracks at their entrances? Now without even touching hives, I am virtually certain; those colonies are dead.
After the robber bees finished removing the honey from the dead colony, the empty combs could easily lead to an assumption of starvation as the colony’s cause of death. Starvation of an otherwise heathy colony would indicate a bee management mistake. Namely, the beekeeper did not provide enough winter stores for the bees. Perhaps that occurred because the beekeeper simply removed too much spring “surplus” honey and failed to recognize the deficiency during the fall feeding. This demise is different from the numerous other complicated scenarios where some difficulty occurred in late summer or early fall, a failing queen with decreased egg production, or a large varroa population along with its complex of RNA viruses preventing the formation of the long-lived winter bees. Over the winter, both maladies can diminish the cluster to a small size, until the bees finally lose contact with their honey, which could have been substantial. In the end, the bees starved, but only as a consequence of previous problems. The difficulty here is not recognizing the loss of all honey by robbing, which would have indicated the colony really did have plenty of honey at the time of its death.
Obtaining the correct conclusion from one’s observations, including not missing important evidence in the hive, is extremely important in bee management. Continuing with this example, if colony mortality over the bee operation was say ….
