The Classroom
The Classroom – January 2026
Q: Female Varroa Behavior
What happens to a foundress Varroa after she emerges from the cell with an adult bee?
A
The word “foundress” is used to describe an adult female Varroa that invades a cell occupied by a honey bee larva and reproduces on the immature bee once the cell is capped. This mite will emerge with the adult bee when the adult bee leaves her cell. At this point, the foundress is in the mobile stage. Many people call this the phoretic stage. However, phoresy describes a behavior where one organism attaches to another organism to use that organism for transportation purposes. This is a commensal relationship (i.e., one organism benefits, the mite in this case, while the other organism, the bee, is neither harmed nor benefits). Adult female Varroa feed on adult bees. They are not using them for transportation purposes. So, this is not phoresy, meaning that Varroa does not have a phoretic stage.
Upon emerging from the capped cell with the new adult bee, the adult female Varroa will feed on adult bees a few days before returning to another cell for reproduction purposes. I keep saying “adult female Varroa” because male mites and immature female mites do not survive once the adult bee leaves its cell. You will only see adult female Varroa on adult honey bees in the nest.
The feeding period is necessary to prepare the female for reproducing once she returns to a brood cell. This period can last 4-11 days when brood is in the hive. It can last all winter when there is no brood in the nest. Reproducing Varroa live one to two months, while overwintering Varroa can live three months or longer. Reproducing Varroa typically invade brood cells two to three times during their life.
Q: Solid vs screened bottom boards
Do you recommend solid or screened bottom boards?
A
If I had been asked this question five years ago, my answer would have been entirely different than today. Screened bottom boards were not a thing when I started beekeeping in the early 1990s. In the mid-to-late 1990s, scientists discovered that replacing a hive’s solid bottom board with a screened bottom board reduced Varroa populations in the hive. The scientists originally theorized that screened bottom boards allow mites to fall out of the hive when bees groom or even when mites lose their footing. I read a paper years ago in which the author summarized the research on mite populations in hives with screened bottom boards compared to those in hives housed on solid bottom boards. From memory, the reduction in mite loads was somewhere between 10 and 15% in colonies housed on screened bottom boards. If this is true, why would one not use screened bottom boards?
A few years ago, my colleague Amy Vu and I started a podcast entitled “Two Bees in a Podcast.” Through it, we interview beekeepers and bee scientists from around the world. Two of our past podcast guests were really interested in insulating hives during winter and summer. They introduced me to the world of honey bee hive thermodynamics, which includes air and heat transfer in the nest. Their basic premise is that our modern hives are terrible places for bees to live from a thermodynamics perspective. For example, compare the wall thickness of our hives with that of a tree trunk in which bees would choose to live in the wild. Our podcast guests made the point that bees work extra hard to thermoregulate in the modern hive and that this work has all sorts of downstream effects on colony health and productivity. This idea really stuck in my head and I have been considering it further in recent months. There still needs to be considerable research in this area, but I think I have been persuaded to think more about hive thermodynamics and colony health.
What does this have to do with screened bottom boards? Well, screened bottom boards allow significant airflow into/out of the nest. I have used screened bottom boards for years, even overwintering colonies with them on the hive, albeit in Florida winters. I know bees can survive with this airflow. Yet, my colleagues pointed out that bees work hard in summer to cool the nest. Where does cool air go? It goes down, right out of the hive. Thus, screened bottom boards may cause thermoregulation problems that bees need to work hard to overcome. The new research has me thinking about the tradeoff between a 10% reduction in Varroa and what bees must overcome to make up for the fact that they have an open bottom on their hive.
For the record, I still use screened bottom boards on my hives, but now I sit those on top of a solid piece of wood that limits air movement through the bottom of the hive. My use of these may continue to change as I learn more about maximizing hive thermodynamics.
Q: Bees not building wax
I am a first-time beekeeper with one hive. Why are my bees not building wax?
A
The lack or cessation of wax production usually has its roots in one thing: limited incoming sugar resources. Bees convert sugar to wax. Oddly, bees prefer to do this with incoming sugar rather than stored sugar. Colonies placed into new hives on new frames of foundation will construct wax if you are feeding them or if there is a sufficient nectar flow. I find that colonies often do not construct wax if you feed them and they already have comb present, or if you feed them at a time of the year they otherwise would not be expanding. The latter is crucial to understanding wax construction.
When do bees construct combs in the wild? They do this when they move into a new home that has no comb, when expanding their nest, or during major nectar flows. Feeding bees outside of these times does not seem to encourage comb construction, even if a fresh flow of carbohydrates is finding its way into the hive.
Consider the following questions to diagnose your colony’s problems.
- Is there a significant nectar flow? If so, the bees would naturally want to build wax.
- If you answered “yes” on the first question, but you still do not see new wax, have you given them foundation on which they can build new comb?
- If you answered “no” to the first question, are you feeding the bees? If not, you should. If you are feeding them on new foundation at a time of the year the colony would naturally expand their nest (spring/early summer), they should be building comb. If you are feeding them when they already have pulled comb or it is a time of year they are not expanding (the second half of summer, fall, winter), they are unlikely to build comb …
