Q: Yellowjackets and Varroa
Can yellowjackets get Varroa from honey bees, from when they raid weak honey bee colonies or when they are on the same plants?
John Andersen
August
Answer
Varroa destructor is only a pest of honey bees (genus Apis). It is not a pest of other bees or insects. Thus, while it is entirely possible that the mite will accidentally end up on a yellowjacket if the yellowjacket is robbing a hive or visiting a flower on which a mite is found, the mite will not survive on the yellowjacket or in a yellowjacket nest. I have never seen a report in which an investigative team found a V. destructor on a yellowjacket.
To expand on this a little, Apis cerana (the east Asian honey bee) is the natural host of V. destructor. This bee is related to A. mellifera and has a similar natural history. It nests in cavities found in the wild in Asia. It builds multiple combs in its nest, stores honey, and is kept by beekeepers in Asia. However, this mite is not considered a major problem for A. cerana, which has natural defenses that allow it to live with the mite. Varroa destructor only became a problem when it expanded its host range to include A. mellifera colonies moved into Asia. This bee (the one kept in the United States and many other areas around the world) is quite susceptible to parasitism and associated damage caused by the mite.
Despite the ability of V. destructor to infest multiple species of Apis, it has never been shown to survive for extended periods on other insects. Of course, anything that enters a honey bee colony risks interaction with V. destructor. In fact, mites have gotten on me multiple times while working colonies. Yet, it does not threaten any other animal beyond some species of Apis.
Q: Mold on the combs
When one of my hives dies over winter, typically there is some mold on the honeycomb, on the frames, and on the inside walls of the hive. Do I need to clean the mold or remove the mold before the bees use the honeycomb, frames, and boxes? Or will the bees clean up the mold themselves? If I need to clean or remove the mold, what is the best method to do that?
Rich Moldenhauer
Minnesota, August
Answer
You are in luck. I just got back from the annual meeting of the Georgia Beekeepers Association. Dr. Meghan Milbrath (Michigan State University) was one of the keynote speakers at the meeting, and she is an expert on hives as pathogen reservoirs. I watched her lecture with interest, and she addressed this exact question. Two weeks ago, I would not have known the answer to your question with any certainty. Now, I know exactly what to say. The mold on your combs is not harmful to bees, and a sufficiently strong colony will clean the mold out itself. Thus, you have nothing to worry about. You can put the combs on a strong hive, and they should be able to take it from there.
Q: Microplastics and honey bees
Swiffer sheets have trapped numerous small hive beetles for me. The oil traps have failed miserably. As fastidious as bees are, what risk of microplastics and other contaminants in the honey can be expected from these sheets?
David Henrikson
Illinois, September
Answer
Microplastics, as the name implies, are small pieces of plastic, usually 5 mm or smaller. As you know, humans use plastics in so many ways, from packaging materials to automobiles, from credit cards to furniture. Microplastics can form by degradation of plastic products, among other ways. This results in microplastics showing up all over the place. I read a news article some years ago in which the author stated that the average human consumes about one credit card’s worth of microplastics every year. We also inhale microplastics.
What do microplastics have to do with bees? Microplastics are considered environmental pollutants. Scientists know they can find microplastics everywhere they look, but it is still not overly clear what microplastics do to organisms. My colleague, Amy Vu (University of Florida) and I co-host a podcast entitled “Two Bees in a Podcast.” In episodes 112 and 131, we interviewed Dr. Mica Buteler from the National Institute for Science and Technology in Argentina. Dr. Buteler has investigated the impacts of microplastics on honey bees, and we discuss this topic in those episodes. You should listen to those episodes as they provide a good overview of the topic.
I also conducted a quick Google Scholar search and, to my surprise, I found a few dozen papers on this topic. To do the same, go to Google Scholar (https://scholar.google.com/) and search “microplastics honey bees.” The funny thing is that I expected to find only a few manuscripts on the topic and I was going to summarize those for you here. Yet, there are dozens of papers, too many to summarize. Instead, I will include a brief list of those papers that provide an overview of the topic more broadly.
Edo, C., Fernández-Alba, A.R., Vejsnæs, F., van der Steen, J.J.M., Fernández-Pinas, F., Rosal, R. 2021. Honeybees as active samplers for microplastics. Science of the Total Environment, 767: 144481. 10.1016/j.scitotenv.2020.144481
Gilani, P.S., Moradian, M., Tajdar-oranj, B., Basaran, B., Peivasteh-roudsari, L., Javanmardi, F., Khodaei, S.M., Alizadeh, A.M. 2025. Microplastics comprehensive review: Impact on honey bee, occurrence in honey and health risk evaluation. Journal of Applied Ecology, 62(8): 1772 – 1794. https://doi.org/10.1111/1365-2664.70030
Al Naggar, Y., Brinkmann, M., Sayes, C.M., Al-Kahtani, S.N., Dar, S.A., El-Seedi, H.R., Grunewald, B., Giesy, J.P. 2021. Are honey bees at risk from microplastics? Toxics, 9(5): 109. https://doi.org/10.3390/toxics9050109
Al Naggar, Y., Ali, H., Mohamed, H., El Kholy, S., El-Seedi, H.R., Mohamed, A., Sevin, S., Ghramh, H.A., Wang, K. 2024. Exploring the risk of microplastics to pollinators: focusing on honey bees. Environmental Science and Pollution Research, 31: 46898 – 46909. https://doi.org/10.1007/s11356-024-34184-y
Rodrigues, K.F.S., Carvalho, B.R.R., Andres, F., Contrera, L., Smith, W.S. Bees and microplastic studies: a systematic review. 54: 56. https://doi.org/10.1007/s13744-025-01268-4
Schiano, M.E., D’Auria, L.J., D’Auria, R., Seccia, S., Rofrano, G., Signorelli, D., Sansone, D., Caprio, E., Albrizio, S., Cocca, M. 2024. Microplastic contamination in the agri-food chain: the case of honeybees and beehive products. Science of the Total Environment, 948: 174698. https://doi.org/10.1016/j.scitotenv.2024.174698
I will note that I browsed the titles of all the papers I found. The work reminds me of research on pesticide impacts on bees. I saw projects on foraging behavior, synergisms with pesticides, accumulation in the bees’ bodies, impairment of behavior, inclusion into honey and other hive foodstuffs, etc. Per my experience with toxicology research, just because scientists report an impact on bees in a study does not mean that it will cause a measurable impact at the field level. Honey bees have colony-level means of overcoming stressors that impact individual bees. Nevertheless, the volume of papers I found indicate that this is a field of active investigation, and it seems that we have much to learn.
The key paper concerning your question is one by Buteler et al. (2023).
Buteler, M., Villalobos, E., Alma, A.M., Silva, L., Tomba, J.P. 2023. Management practice for small hive beetle as a source of microplastic contamination in honey and honeybee colonies. Environmental Pollution, 334: 122151.
https://doi.org/10.1016/j.envpol.2023.122151
In that study, scientists put microfiber wipes into hives to control SHBs. Then, they looked for microplastics in the hives. From the abstract of that paper, the authors found microplastics in the guts and cuticles of honey bees in hives in which the microfiber wipes were used. They also found it in the honey in these hives. What does this mean for bee and human health? The jury is out on this, but the review papers I cited earlier are good places to start …
