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Bees & Beekeeping: Present & Past

A Hive Cleanup in the Aftermath of Small Hive Beetles: Part 1

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

In my July 2022 American Bee Journal article, we saw how small hive beetles can evict a colony off its combs. Now with the approach of summer, the time is appropriate for another small hive beetle article, not like the previous one. This article is more from a beekeeper’s perspective confronting the typical symptoms of a difficult cleanup. Here we will deal with the problem in detail along with numerous technical photographs, some I have been saving for years to properly illustrate this topic.

In this article, we consider the small hive beetle not as the primary cause of the colony’s destruction, more as a scavenger, opportunistically exploiting weak or dying colonies for its reproduction. (In some situations, the small hive beetle can be seen more like a predator.) Let’s begin.

Last summer, I was driving the bee truck between apiary locations when something unusual happened –– my cell phone rang. The number is mostly for emergencies. Even so, not many people have the number. After stopping the bee truck off the road, I answered.

A rather excited local beekeeper told me his best hive, stacked with spring honey supers, was oozing slime out the entrance slot. I had a full workday planned in my out-apiaries. While listening, hearing his description and distress, I mentally tossed all my bee jobs into an imagined trash can, until the remaining workday was wide open and free. I requested he not open the hive until I got there. Then we would examine the hive together. Having endured alone my first slimed-out hive, I think the experience is best shared with one who has seen such gruesome things.

Figure 1 (left) shows the hive. From several feet away, the odd cluster on the corner is suspicious, and warrants a closer examination. As part of my current colony diagnostics, any odd clustering, whether in the spring, summer, or fall, has to be closely investigated. Unusual clustering on the hive could indicate deadly colony conditions (small hive beetle eviction in the spring or summer; usurpation in the summer).

The colony history is important, similar to the medical field when the doctor needs to see a patient’s medical records. I found out the beekeeper had split a nuc from the colony several weeks earlier. The mother queen may have gone with the nuc, and the parent colony did not produce another laying queen. The mother queen could have remained in the hive and the colony swarmed, and even afterswarmed, then failed to produce a laying queen. The bee population would then decrease until the bees could no longer protect the combs. If the bees remained queenright (no dequeening or swarming), they could have succumbed to varroa and its complex of RNA viruses.

Strong colonies crashing because of exponentially (fast) growing varroa populations is thought to be a typical occurrence. A large bee population does not ensure colony survival, although the notion is attractive. For example, a large cluster survives the winter better than a smaller one. From heat production and retention (insulation), the large cluster has the survival advantage over a smaller one. Winter cluster survival involves several important factors, more than just the number of bees comprising the cluster. A critical one is the presence of long-lived winter bees, special physiological bees with enhanced fat bodies. These bees normally appear toward the end of the active bee season. It has been shown that varroa interrupts the development of these special winter bees. A large cluster lacking them, being comprised of short-lived summer bees, going into a long winter is expected to dwindle away to nothing by spring. Its large cluster size offered no protection.

Most of the bees were on the outside of the hive as shown in Figure 1 (right). That many bees could not adequately cover the combs in such a tall hive. Assuming a swarm (with a queen) did not just abscond a few days earlier, leaving those bees, the colony had probably been queenless for a long time. The colony population decreased until the bees could not properly protect the combs and the adult beetles began laying thousands of eggs in them. If the amount of slime produced by the beetle-vectored yeast, and perhaps other associated microbes, is large enough and the viscosity (runniness) is low enough, then it slowly drips from the entrance slot as shown by Figures 2 and 3, aided by the forward hive tilt.

The hive still had its spring honey crop. The cleanup began by working down through the honey supers to see what honey might be salvageable for bee feed only. In Figure 4 (left), we have removed the top cover, not knowing the extent of the damaged combs below. Figure 5 shows a comb of honey from Super 1. The small hive beetle damage was minor with a minimal slime layer over the cell caps and no beetle larvae. Super 2 had a little more slime, no beetle larvae either.

A strong colony could clean up these supers. They go on top of the strong colony, only one on the hive at a time. When using bees to clean up contaminated comb, do not give them too much at one time. The goal is a rapid cleanup. Specifically, for a strong colony, occupying two deep supers and one medium super, I would only give one capped honey super (like Super 1 without adult or larval beetles). I want the bees to cover the combs in less than 12 hours, usually in a few hours.

Currently my recommendation for comb cleanup by the bees is not giving them any pollen cells no matter the level of contamination, even if minor. Just discard the pollen combs as not salvageable. Once fermented even to a small degree, the pollen is probably of no value to the bees. Certainly saving the pollen does not compare to the risk of exposing the cleanup colony to potentially large “doses” of the destructive yeast that small hive beetles are known to carry, and that readily grows in the stored pollen. Besides bees being slow to accept (i.e., walk on) these pollen combs (on their cell rims) if they do, they could potentially track the microbes to other regions of the colony (forming a transmission route). The uncontaminated pollen bands of the colony’s brood nest would be of particular concern. Given all the unknowns here, the safe solution for the health of the bees means I discard the pollen combs.

Back at the slimed-out hive, the lack of beetle larvae is not surprising. I figured most of them were mature larvae ready to wander (when they leave the hive to find the soil for pupation). Perhaps the capped honey in the supers far from the entrance became contaminated when the mature larvae began wandering from the brood nest, where they develop. Quite likely, some larvae had already left the hive. For now, it is best to methodically inspect the supers, proceeding down to the brood nest.

Figure 4 (right) shows the bees breaking cluster on the outside of the hive, wanting to get inside, going up and into Super 3. Tipping up Super 3, honeycombs bulge from the narrow bottom bars and are easier to see across the super. The combs have more slime on them. Super 4 below had a similar comb condition, or slightly worse (see Figure 6). The structural strength of these combs remained intact. To try and salvage them, first use water under pressure from a hose to mechanically remove at least part of the slime. Some beekeepers include a “detergent” as a cutting agent to better remove the slime. I have not tried that.

From an organic chemistry perspective, I do not know what kind of “detergent” they mean. Different detergent molecules carry a positive or negative charge, or both an excess of positive and negative charges, but in different regions of the detergent molecule. The zwitterion, as it is called, has no overall net charge for the entire molecule (the positive and negative charge amounts cancel out to zero). To be most effective, the “detergent” should be matched to the chemical properties of the material being removed, the slime, which is expected to vary.

Of critical importance however, if using a “detergent,” make sure to completely rinse the “detergent” away before giving the combs to the bees for the final cleanup. In general, soapy water solutions are very detrimental to bees (and other insects). In mellitology, the general study of all bees, encompassing more than 20,000 species of them, field survey traps are used to estimate the bee fauna at a location. Trap designs are numerous. Some consist merely of vertical bright colors to attract the bees. After trying to land on the colors, the bees simply fall down into a liquid solution meant to hold them there, no climbing out and flying away. The solution –– soapy water.

Under Super 5 and over the brood chamber, mature small hive beetles scattered for the dark ….