The Beekeeper’s Companion Since 1861

The Classroom

The Classroom – October 2021

- October 1, 2021 - Jamie Ellis - (excerpt)

The Classroom - ABJ - Jamie Ellis
Q  Bubble Butt?

 This year, I have found what I call “Bubble Butt.” See attached photo [Figure 1 – the boxed bee]. I have seen one or two bees with a gelatinous attachment hanging off their abdomens. I do not think it is Nosema. This has occurred in my own apiary as well as the College of Charleston hives where I mentor graduate students. Any ideas?

Nancy Simpson
South Carolina, August


What you have photographed is a bee that got squished while you were working the hive. Basically, it was mashed to the point that some of its organs popped out of its abdomen. I see this quite a bit. It is common to squish a bee as we remove frames, shift supers, etc. Such activities can put pressure on a bee’s abdomen and push out part of its organs. The good news is that what you are seeing is not contagious. The bad news is that the bee will perish.

One of the saddest things in the bee world to me is the knowledge that I am going to kill bees just by virtue of working a colony. I have always done my best to move frames slowly, gently rock supers when I return them to the hive, etc. Inevitably, though, bees get killed even on the best of days. I hate hearing that little crunch when I am reassembling a hive!

Q  Overwintering Nucs

 I have been told that it works well to overwinter weak colonies in five frame nucs. Is there anything to that? Does it take a special type of nuc? And what happens in the spring?

Darrel Beachy
Illinois, August


I have a couple of thoughts about this. First, I would want to know why the colony was weak in the first place, leading to it needing to be scaled down into a nuc. Is it weak because the queen was failing, high Varroa populations, not enough food, etc.? If so, these may be issues that cannot simply be remedied by scaling the colony down to a nuc and then trying to get it through winter. The stressors would need to be addressed first. Sometimes, scaling it down into a nuc can help the colony concentrate its effort to address whatever the problem is. However, the bees may need other help from you as well, depending on what led it to be weak in the first place.

If, on the other hand, the colony is weak because it is new, a recent split, a fresh swarm, etc., but is otherwise healthy, then I would consider overwintering it in a nuc with a few caveats. I have overwintered plenty of nucs in my time. However, I have always lived in the southeastern United States, where the winters are considerably milder than in northern states and where I can expect temperatures warm enough to support bee flight off/on throughout winter.

I notice that you live in Illinois. This concerns me a bit given your bees experience much colder winters than do mine. Colonies need to be of sufficient size to be able to thermoregulate (keep warm in this case) properly. The bees use stored honey as the energy source for the heat they generate. Nucs, by nature, are not large hives, giving the bees less room to store the honey they need for thermoregulation. That is why many beekeepers in northern states overwinter in double deep hive bodies as their standard hive configuration. This allows the colonies to be strong heading into winter and to have stored enough honey to support their general activity.

I would suggest chatting with beekeepers in your area to see if they have been able to overwinter nucs successfully where you live. I am certain that they will have some pointers for you. If they have been able to overwinter nucs successfully, they likely use 5-frame nucs for multiple reasons. First, 5-frame nucs are the largest nuc size available, allowing the colony within to reach critical mass for thermoregulation. Second, 5-frame nuc equipment is more readily available than is equipment for the other nuc sizes. You can even overwinter them as double-deep nucs (though at that point, why not just a single 10-frame deep?). Medium supers are also available for 5-frame nucs, thus giving you an opportunity to ensure they have enough stored honey for winter. I cannot stress enough, though, that chatting with local beekeepers about their success overwintering nucs is super important. Assuming they can overwinter well where you live, the nucs usually hit the ground running, ready to grow into production colonies in spring.  

Q  What is this?

I have five hives in my yard. I happened to notice a bee [Figure 2] land on the fence near my bee fountain and discovered that this bee was flying while clutching a honey bee [Figure 3]. Can you please look at this picture and explain what is happening?

Laurie Ihm
New Mexico, July


What you are seeing is not a bee but rather is a fly from a family of flies called robber flies (family Asilidae). This family is composed of many species of flies that are finely tuned hunters. They usually catch their prey mid-flight, being able to grasp their prey with spines that line their legs. After catching their prey, they typically land on a structure such as a fence, tree branch, etc. There, they use their large, beak-like mouthparts to pierce their prey and feed on their soft tissues. Robber flies can have favorite places to land with prey. If you find one of these locations, you can often see a pile of carcasses beneath where they perch, the carcasses being the bodies of all the prey they have eaten. Super cool, I know.

There are some species of robber flies that actually look like large bees. They are usually mistaken for bumble bees or carpenter bees. The fly in Figure 2 looks just like a large bumble bee! Amazing! This particular fly, as you note in your question, actually will hunt honey bees, capture them mid-flight, perch on a structure (the fence you show in Figure 3), and then eat the bee. You sent me this question in July, which is exactly when I see countless robber flies in my backyard eating my honey bees. As a beekeeper, I have always been worried about the impact they have on my colonies. As an entomologist, I have come to discover that they do not do much damage and typically are not worth trying to control.

I am not a robber fly specialist so I cannot tell what species you have in New Mexico. However, someone in our department at the University of Florida authored a document on robber flies. It includes a photograph of a fly very similar to the one you have. You can find the document, and learn more about robber flies, by Googling “EDIS robber fly.” You can also see a lot of good images and discussion about robber flies if you Google “robber fly bee eater.” So, it is a little sad that it is eating your bees. The good news is that it likely is of minor consequence… .