Q: Plants as Varroa control
After reading the February 2026 issue and reflecting on my few years of beekeeping, I have Varroa on the brain. Are there any plants that bees frequently visit that have a negative effect on Varroa? Can honey bees visit them enough and bring back pollen and nectar to help control population? If so, how could it be used in and around the hive to help the bees?
Sarah Merritt
February
Answer
Possibly, but this is an under-investigated research topic. Let me explain. First, we know that various botanical extracts have activity against Varroa. For example, thymol and oxalic acid both naturally occur in some plants. Both are also known to control Varroa. However, I do not think honey bees get enough of these compounds naturally, either accidentally or purposely, while foraging to be useful against Varroa.
Your questions lie at the heart of the scientific concept of self-medication. In the context of honey bees: Is there evidence that honey bees can self-medicate? Can they collect substances that seem to help them/their colonies fight diseases or pests? The data suggest that honey bees can self-medicate. For example, Simone-Finstrom and Spivak (2012) showed that colonies exposed to the fungal parasite that causes chalkbrood increased their resin foraging rates (i.e., they were collecting more resin, possibly to fight infection with chalkbrood). Gherman et al. (2014) showed that bees infected with Nosema preferred to consume honeys that had high antibiotic activity. Erler and Mortiz (2016) provide a review of this topic for honey bees. Check out Abbott (2014) if you want to see a broader review of this topic across insects.
The take-home message is that there is evidence that honey bees self-medicate. In a 2018 paper, Pusceddu et al. showed that colonies with high loads of Varroa increased their resin collection. Pusceddu et al. followed this up with a 2021 paper in which they suggest honey bees use propolis to, among other reasons, control pests, or at least they benefit from the pest-controlling ability of propolis. Superficially, this may suggest that bees respond to Varroa by self-medicating, but we are in the early stages of understanding this behavior. At the limits of our current knowledge, the few plant-derived compounds known to impact Varroa most (i.e., thymol, oxalic acid, etc.) come in labeled products you can use against the mite. More work needs to be done, but I would not be surprised if someone, someday, showed that a particular plant was good for bees.
Abbott, J. 2014. Self-medication in insects: current evidence and future perspectives. Ecological Entomology, 39(3): 273 – 280. https://doi.org/10.1111/een.12110.
Erler, S., Moritz, R.F.A. 2016. Pharmacophagy and pharmacophory: mechanisms of self-medication and disease prevention in the honeybee colony (Apis mellifera). Apidologie 47: 389–411. https://doi.org/10.1007/s13592-015-0400-z.
Gherman, B.I., Denner, A., Bobiş, O., Dezmirean, D.S., Marghitas, L.A., Schluns, H., Mortiz, R.F.A., Erler, S. 2014. Pathogen-associated self-medication behavior in the honeybee Apis mellifera. Behavioral Ecology and Sociobiology, 68:1777–1784. https://doi.org/10.1007/s00265-014-1786-8.
Pusceddu, M., Piluzza, G., Theodorou, P., Buffa, F., Ruiu, L., Bullitta, S., Floris, I. and Satta, A. 2019. Resin foraging dynamics in Varroa destructor-infested hives: a case of medication of kin? Insect Science, 26: 297-310. https://doi.org/10.1111/1744-7917.12515.
Pusceddu, M., Annoscia, D., Floris, I., Frizzera, D., Zanni, V., Angioni, A., Satta, A., Nazzi, F. 2021. Honeybees use propolis as a natural pesticide against their major ectoparasite. Proceedings Biological Sciences: 288(1965): 20212101. https://doi.org/10.1098/rspb.2021.2101.
Simone-Finstrom, M.D., Spivak, M. 2012. Increased resin collection after a parasite challenge: a case of self-medication in honey bees? PLoS One, 7(3): e34601. https://doi.org/10.1371/journal.pone.0034601.
Q: Supersedure cells
You once enlightened me in a Classroom entry that queen supersedure cells are made from worker cells/larvae, not from established queen cups. You stated that queens will only lay in queen cups during swarming. I am having a hard time explaining this to other beekeepers. Some seem to believe that queen cups are the origin of all queen production. Others seem to believe, like I did, that the workers make queen cups for the purpose of supersedure. Beekeeping handbooks and textbooks are noticeably vague about this distinction, which is why I had so often wondered why queens would lay eggs in queen cups in order to replace themselves, and
not to swarm.
So, I am looking for a citation, if possible, on the construction of swarm vs. supersedure queens, something that I can use to back up my assertion that if you see a queen cup, regardless of the position, it is meant for swarming. By queen cup, I am referring to the downward-facing cells built for the purpose of queen production BEFORE there is an egg or lava inside.
I looked this up the best I could in “The Hive and the Honey Bee” and “ABC and XYZ of Bee Culture” and the results were even more disappointing. “The Hive and the Honey Bee” states outright that queen cups are made for the purposes of supersedure. It does not explain what prompts a queen to lay eggs in them. It says only emergency queens are reared from worker larvae. The “ABC and XYZ” of Bee Culture is a bit vaguer but also states that cups are made for supersedure.
I think the most frustrating thing is the implication that relied-upon texts might be wrong. I think it is a critical distinction between rearing a queen from start as an egg in a queen cup vs. converting a worker larva. I think most of the beekeeping world assumes supersedure cells start as cups and the mother queen lays an egg in it. Am I right to believe this is wrong?
Chris Hagwood
March
Answer
Well, this is not an easy question to answer. Most of what I know about this topic comes from my personal experience plus what I have read in the books/journal articles. We all seem to say the same thing about queen cups, queen cells, swarming, and supersedure. A lot of it comes down to semantics. Thus, the answer that follows is how I think about this topic.
Swarming is a planned event. The colony wants to swarm. Consequently, workers build queen cups. Queens lay in the queen cups. Workers develop these into queen cells. Beekeepers typically call these “swarm cells.” That is simply another phrase for a queen cell built for the specific purpose of swarming. Swarm cells often occur on the periphery of the comb.
Supersedure can be planned (i.e., the bees do it in response to a failing queen) or emergency (i.e., the bees do it in response to a dead/missing queen). For emergency supersedure, there is no queen to lay an egg. Consequently, the queen cannot lay an egg in a cell in which her replacement will develop. The workers must go to existing female larvae developing in worker-sized cells to redirect the larvae from the developmental path of workers to those of queens. These supersedure queen cells tend to occur among the brood pattern on the face of the comb.
Planned supersedure is harder to understand and it is really the type of supersedure about which you are asking. I searched Google Scholar using a variety of terms and could not get a clear answer. The consensus, if there is one, is that queen cups exist in the hive and that queens may lay in them when they are present. Sometimes, the workers will carry that cell to completion, initiating the supersedure process. My guess is that they only do this when the mother queen is failing. Other times, the workers will tear down the cell containing the egg/young larva to stop the supersedure process. The queen likely does not know that she is laying an egg that will lead to her replacement. She, instead, is likely simply laying in the next empty cell she encounters.
To summarize: During emergency supersedure, queens are often reared from eggs or larvae in worker-sized cells. During planned supersedure, queens may also be reared from eggs laid by the mother queen into a queen cup. Like you, I was surprised to find little research evidence for these assumptions.
