The Classroom
The Classroom – June 2022
Q Ideal hive entrance size
[Using a standard entrance reducer], I keep [my hive entrances] at the smallest entrance throughout the season to help in defense and to replicate natural bee tree openings (Figure 1). My teaching partner opens his hives to the maximum [size] to make it easier for foragers and to help with temperature regulation. What is the best practice?
Nancy Simpson
South Carolina, March
A
I have not seen any applied research on this topic. I am aware of Dr. Tom Seeley’s research that shows swarming bees prefer nest sites with smaller entrances (~3 inches2, 19 cm2). This, presumably, helps with nest defense and possibly even thermoregulation. Thus, one could make the argument that we need to provide honey bees with hives possessing the nest site characteristics that the bees would choose themselves. However, I have never seen a study in which the productivity and health of colonies living in hives with reduced entrances are compared to those living in hives with completely open entrances. Most beekeepers, myself included, simply use hives with their entrances in the most open state (i.e., with no entrance reducer at all). I am not sure that is “best practice,” but it is certainly the common practice. I can also share that we leave them wide open with our university research hives. I have never really felt that this was a problem for the bees. However, that is just based on anecdotal experience. We do reduce entrances when robbing is bad, or even during winter.
As a quick aside: I completed my Ph.D. work at Rhodes University in South Africa. I conducted all of my research using honey bees native to the region. It was VERY common for bees in my test colonies to reduce their entire entrance to a few inches using propolis. In fact, having worked only with European-derived honey bees in the U.S. until I moved to South Africa, I was stunned that the bees would do this. I even have great pictures of bee colonies nesting in cliffs. When bees do this, an entire side of the nest is exposed, given that a cavity in a cliff is basically a recessed area with a gaping opening on one side. The bees choosing these nest sites built entire walls of propolis to reduce the nest entrance to a few openings that totaled around 3-4 inches2. Fascinating!
Q Sugar shakes for Varroa monitoring
Can you please give me your opinion on doing sugar shakes to MONITOR your hives? One of our bee club members said that you stated that it does not work. I just want to clarify this?
Bernadette Cieslak
Ohio, March
A
I am grateful that you emphasized MONITORING in your question. I am grateful because powdered sugar is a reasonable monitoring tool for Varroa but it is not a good control for Varroa. Let me explain.
I was a postdoctoral researcher at the University of Georgia from 2004 to 2006. Around that time, many beekeepers were beginning to suggest that you could dust colonies with powdered (confectioners’) sugar to control Varroa. This was a hot topic and many people were touting the benefits of dusting colonies. The premise was that the dust would either (1) cause the bees to groom themselves, thus knocking off Varroa, or (2) stick to Varroa’s “feet,” causing them to lose their grip on the bees. Couple these proposed modes of action with screened bottom boards, and you would (hypothetically) get Varroa falling out of your hive every time you dust your bees.
Well, this was all a good idea until science got in the way. ☺ My wife Amanda was among the first group of scientists to look at the practice of dusting colonies with powdered sugar to control Varroa. Other scientists had already shown that dusting colonies would increase mite fall, something they determined using sticky screens placed under the brood nest. Yet, Amanda carried it further and looked at Varroa populations in colonies after dusting. She found no impact of dusting on Varroa populations. Since then, other scientists have conducted similar projects and made similar discoveries. Long story short: Dusting colonies with powdered sugar is not a good way to control Varroa, mainly because it does not control Varroa.
That said, you can use powdered sugar to monitor for Varroa. You do this via a process called the “sugar shake” method. This method is similar to an alcohol wash, but you use powdered sugar, rather than alcohol, to dislodge the mites. For this method, you collect about 300 adult worker bees in a glass canning jar (or any of the commercial products that were made for this purpose). You close the jar with a screen mesh lid rather than a solid lid. Then, you place about two tablespoons of powdered sugar in the jar, through the mesh lid. You gently roll the jar for a few seconds, and then place the jar on a surface, where you allow the bees to mix in the jar for two minutes. Following this, you invert the jar and lightly shake the powdered sugar, and dislodged mites, out of the jar through the screen mesh lid. You can shake the contents into a tub of water which will help dissolve the sugar, making it easier to count the mites.
There are a few pros/cons associated with this method, especially when compared to alcohol washes. The first pro is that you do not kill the bees with sugar. The alcohol wash version of this method does kill the bees. The second pro is that this is pretty easy method to do in the field.
I see two main cons of using method. First, the sugar can make things sticky in the field, especially when it gets moist. Second, and most importantly, the powdered sugar shake tends to underestimate the number of mites in the jar. It just does not seem to dislodge the mites as well as shaking bees in alcohol does. Nevertheless, I tend to recommend this method when someone wants a quick way to screen Varroa levels when trying to make treatment decisions. (Remember: Treat when you hit the economic threshold of ~3 mites/100 bees.)
In conclusion, powdered sugar is not a good control option for Varroa while it is a good screening tool for Varroa.
Q What lines brood cells?
What material makes up the thin brown hexagonal cells that are left when I put brood comb in a solar extractor? What is the brown lining that builds up in brood cells? Is it the cocoon the larva spins once sealed in [the cell], or the remains of the shed cuticles? It is very thin and does not look like layers [deposited over time]. While searching for an answer, I came across this:
“When worker bees prepare wax cells for the queen to lay new eggs, they brush and polish the interior walls of the cell using propolis.”
So is propolis part of this material?
Patricia Holden
England, March
A
Honey bees construct all of their comb out of mostly pure beeswax. I say “mostly pure” because the wax can become slightly adulterated during the comb-building process. The wax bees use to make comb in which they store honey is the same as that in which they rear brood. Yet, as you note, the wax in which brood is reared looks much different than that used to store honey. The more brood is reared in a section of wax, the darker the wax becomes. So, what is happening to this brood comb?
First, you correctly point out that worker bees will polish (clean, smooth, and shape) brood cells to ready those cells to receive an egg laid by the queen. This process includes worker deposition of small amounts of propolis (plant resins) on the cell walls. Second, developing honey bee larvae secrete a type of silk, effectively spinning a thin cocoon in their capped cell. A lot of this silk gets incorporated into walls of the cell over time. Third, developing bees shed their exoskeletons while they develop. They do this six times in fact! These cast skins compose part of the debris that can build up in cells over time. Fourth, the larvae defecate in their cells immediately prior to pupating. Fifth, other types of debris can end up in cells as bees walk on the comb, drop debris into the cells, etc.
Finally, conditions produced by pests and pathogens can cause the buildup of stains and debris in cell walls. For example, Varroa defecate in cells. Larvae that die to European foulbrood darken and can stain the cell walls. Of course, worker bees try to remove all of these adulterants from cells when cleaning the cells, readying them for the next egg. However, they fail to remove a little of this debris every time the cell is used. This causes the cell to accumulate these adulterants over time, ultimately giving the brood comb the characteristic black color it turns as it ages.
Honestly, by the time the brood combs age significantly, the cells can become more “other material” than they are wax. I see this when I put really old brood combs in the solar wax melter. When I do this, I hardly get any wax in return. However, what wax is present melts away from the cell walls, leaving the black, tube-shaped capsules that that you see in your wax melter.
Q What is on this bee’s thorax?
I noticed several smaller weak and dying bees on one of my hive entrances. They have a prolapse on their thorax (Figure 2) that I am not familiar with. Could you look at this photo and give me your thoughts?
Lance Alexander
Indiana, April
A
Thanks for sharing the picture. I have slowly developed a love for and appreciation of honey bee anatomy over time. I knew very little about it when hired by the University of Florida. In 2011, I began teaching a course on beekeeping at UF and this forced me to learn the external and internal anatomy of honey bees. Shortly after that, I contributed to a book chapter on honey bee anatomy. After that, I was hooked. Honey bees are wonderfully designed. There are quite a few really great books on honey bee anatomy. Have a look. You will be impressed!
My team and I conducted a research project on two subspecies of honey bees that are present in …
