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American Bee Journal

The Classroom – June 2024

By July 8, 2024No Comments
Q More on Comb Orientation

Regarding your [May] answer regarding cell orientation in the nest: I recently left a half frame flat [horizontal] in an eke [spacer] on top of a colony to let them clear out some old feed that was still [in the frame]. A week or three later, [upon] returning to the hive, I discovered the downward facing cells contained eggs, so [I] wondered how that would turn out. I left [the bees] to it. The queen had space to lay around the edges of the brood nest. This frame was directly above the brood. Last time I looked, the cells were capped with [worker brood]. I will get around to righting the frame and slipping it into a nuc.
Calum Grigor 
Switzerland, March

A

Thanks for providing your insight. This is a very interesting observation. What I discussed in May, and Dr. Smith addressed in the preceding question, concerned combs rotated 90°, but with the cells still oriented horizontally. You are discussing rotating a comb 90°, but with the cells oriented vertically, with the opening of cells on one face of the comb pointing down and other face of the comb pointing upward. I love that the queen still laid eggs in those cells and that the bees had the intuition to rear worker brood. I think the take-home message from this is that bees are very resilient and can adjust to many situations. I suspect combs can be out of place naturally for several reasons. For example, bears or strong winds could turn hives on their sides, upside down, etc. In these cases, the bees would need to be able to adjust how they use combs to survive. They do prefer to build their combs a certain way, but it is nice to know that they can adjust when needed.

Q Screened bottom boards

I have been beekeeping several years. When screened bottom boards came out, I tried them a couple years. I switched back to solid bottom boards in the winter every year to keep the colonies warmer. It was a hassle switching back and forth so the last couple years I left the solid bottom boards on all year. Since spring has arrived, I’m wondering if the screened bottom boards really make a significant difference in the mite population and is it worth it to put them back on the hives? Also, would an open screened bottom board be any benefit for hive beetle control? I always leave the bottoms opened without the slider in place. I’m interested in using the screened boards for mite control, not monitoring. I do alcohol washes for mite counts.
Priscilla Bonsell
Pennsylvania, March

A

I have not been asked a question about screened bottom boards in quite some time. The second research project I ever conducted, and ultimately published (in the American Bee Journal in 2001 no less), was on the efficacy of bottom screens (Ellis et al., 2001). In that study, I showed that colonies housed in hives with screened bottom boards had ~15% lower Varroa populations than did colonies housed in hives with solid bottom boards, though this difference was not statistically significant. One interesting note about screened bottom boards in this study is that they improved the efficacy of Apistan. This mite-control product seemed to perform better when applied to hives with screened bottom boards.
The Honey Bee Health Coalition publishes a guide entitled “Tools for Varroa Management” (https://honeybeehealthcoalition.org/resources/varroa-management/). In it, they provide a summary table on the general efficacy of screened bottom boards. They claim that it can reduce Varroa populations about 5-10%. That seems on par with what I typically see in the research literature.
Your question, then, is quite relevant. Are screened bottom boards worth using? I will start from the top for the benefit of the reader. Screened bottom boards, as the name implies, are bottom boards that are screened rather than solid. That simply means that they contain mesh on the floor, rather than solid wood. The use of screened bottom boards started in the late 1990s, when some investigators wanted to determine if they would provide any level of Varroa control. I believe a research paper or two had been published on this idea before I tested it and published my paper with colleagues in 2001.
The idea behind their efficacy is that bees routinely groom Varroa from their bodies throughout the day. In hives with solid bottom boards, a Varroa falls to the bottom and simply mounts the first adult bee that passes its way. When solid bottom boards are replaced by screened bottom boards, the mite falls through the screen, to the ground, unable to infect another bee. I once heard an alternative explanation that the screened bottom boards may impact mite invasion into brood cells, so I guess its actual modus operandi is unknown. Nevertheless, colonies with screened bottom boards tend to have 5-15% fewer Varroa than colonies without them. Does that make them worth using? Well, it depends on what else you do to control Varroa.
To me, any reduction in Varroa is better than no reduction at all. My opinion the last two decades is that you need a bottom board on the hive anyway, so why not use a screened bottom board? That opinion caused me to use them in my own hives and at our laboratory the last 20 years. I believe that, coupled with using resistant queen stock and other cultural/mechanical/genetic control measures, screened bottom boards are a useful integrated pest management (IPM) tool for Varroa. They will not eliminate the need to treat for Varroa. I just think they may reduce the number of times you have to treat — again, when used as part of an IPM program.
Can they be used year-round? I have left them on hives year-round in Georgia (my home state) and Florida (where I live/work now). At one time, I did close the screened bottom boards during winter using a plastic panel I would slide into the hive entrance, over the screen. I quit doing that a few years ago, opting to leave the screens open throughout winter. I would not do that if I were trying to overwinter colonies in the central and northern U.S. I would either replace them with solid bottom boards during winter, or close them using a piece of plastic I slide into the hive. I do not think I would covert solid bottom boards to screened bottom boards in existing hives. However, I would strongly consider giving them a try when creating new hives.
Do they work against small hive beetles? You are in luck! I wondered the same thing 20 years ago and conducted that test with colleagues as well (Ellis et al., 2003). Screened bottom boards had no measurable impact on small hive beetle numbers in one test apiary and seemed to help just a little in a second test apiary. The verdict: They do not seem to encourage small hive beetle infestations, so I would not hesitate to use them against Varroa, resting assured that they would not exacerbate small hive beetle problems.
At the end of the day, you may find that they are not worth using in your operation. I suspect they are not equally beneficial in all situations. Check out the Honey Bee Health Coalition’s information on this topic and decide if you want to continue/discontinue their use in your operation.

Q Two Queens

I have been maintaining an observation hive at the Long Island Children’s Museum for over a decade. One of the benefits for the beekeeper is that lots of people are around to look at the bees and sometimes they see something I missed. Last fall, they informed me that there were two queens in the hive.
At first, I agreed that it was interesting, but I didn’t expect it to last. The colony had swarmed late last summer and since the original queen was marked, and I had hived that swarm, I have to believe they simply allowed a second queen to survive longer than usual after they raised the successor. (I learned a few days ago from one of the staff at the museum who has taken great interest that she has clearly observed that both queens are actively laying.)
At this point, all these months later, I am only troubled by the fact that after searching the literature I am still not able to tell anyone how common this is. As my friend Rich said to me, when most beekeepers see a queen (or just eggs) they stop looking. I am, clearly, guilty of that. “… maybe it’s more common than we think.”
Perhaps you or your readers can help answer the question: How common is it?
Carl Flatow
New York, March

A

Yes. Yes. Yes. I have seen this many times and talk to my research team about this constantly. Great observation on your part. I attended Rhodes University in South Africa for my Ph.D. research. I did this for many reasons, one of them being that I had funding to study small hive beetles, a new bee pest in the U.S. at the time, in its native range. This was a very exciting time for me.
While in South Africa, I conducted a significant amount of behavioral research using observation hives to investigate how honey bees interact with small hive beetles in the nest. I was in South Africa for three years and constantly had 1-3 observation hives up and running while there. I remember vividly the first time I saw two queens in one of those hives. I saw a queen on one side of the hive, moved to the other side to continue my observations, and then noticed a second queen. After that, I noticed the same thing happening in other observation hives I was using. I always found this alarming at first, as if having two queens was something I needed to fix in the hive. However, usually within a month or two, the colony was back down to one queen, seemingly being no worse in the process. This is only an anecdotal observation, but I bet ~20% of my observation hives had two queens.
I was fairly convinced that this was a trait of African honey bee colonies, and that I would rarely see this condition upon returning to the U.S. and working colonies of European-derived stocks of honey bees. Yet, that conviction turned out to be wrong. I purchased three nucs when I arrived back in the U.S. and had eleven full-size colonies the next year. To my surprise, I would frequently see two queens in those colonies, during certain times of the year. I would have not believed my eyes had I not seen the same thing while in South Africa. Does this really happen frequently?
Well, I have no data to speculate about the actual frequency that this occurs. However, I suspect it happens more frequently than beekeepers know. Why do I feel this? I think beekeepers, myself included, routinely overlook the obvious when it comes to the possibility of having two queens in a hive.
This is how it happens. You open a hive, search a few combs, and then find the queen. For the sake of illustration, let us say you find the queen on frame four. You return frame four to the nest, move through a few more frames, and then find the queen…

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