The Classroom – January 2021
Q Mystery debris in the brood
Do you know what these black specks are?
Great pictures, Chris! These are wax moth feces. You sent a couple of pictures so let me explain what you see in both. In the first picture (Figure 1), you have opened a drone cell to expose a developing drone that has black specks on it. In the second image (Figure 2), you removed the drone pupa and can see black specks all over its body.
I am going to be an entomology nerd here … but these specks are the color and rough shape of feces for many moth caterpillars. I have seen the feces of various moths so many times that it finally occurred to me when I saw something similar in a hive before that I was actually seeing wax moth feces. Initially, I, too, was perplexed when I had seen these in the past. However, I ultimately figured out what I was seeing based on observations of other moths. For example, I happen to have some trees in my yard that some species of moths like to use as oviposition (egg-laying) sites given that their offspring eat the leaves of the trees. At certain times of the year, the ground underneath these trees is littered with caterpillar feces of similar shape and color as those you see in the pictures you sent.
I actually get emailed similar pictures by beekeepers, maybe one picture every couple of years. I finally put two and two together and recognized the specks for what they were. Now, why are they there? We have two species of wax moths that inhabit our hives: the greater and lesser wax moths. As you might imagine, the greater wax moth is the larger of the two species. Both, though, can be found in/around hive equipment.
Female wax moths lay their eggs in the hive. The caterpillars that emerge from those eggs will tunnel at the comb midrib (the foundation of the comb on which both sides of the comb are built) or just under the cell cappings. Incidentally, the greater wax moth larva tends to tunnel at the comb midrib while the lesser wax moth tends to tunnel just under the capping of the brood cells. As a result, both cause different conditions in the brood. Greater wax moth caterpillars produce silken tunnels as they feed near the midrib. The silk can actually cause bees that are ready to emerge from their cells to get stuck in their cells. The silk literally sticks them to the bottom of the cell. This leads to a condition called galleriasis where you see a group of bees trying to emerge from their cells, but unable to do so. They sit there and wiggle until they ultimately starve to death. Lesser wax moth caterpillars, on the other hand, tend to tunnel just under the cell capping. This tunneling behavior results in the loss of cell cappings on adjacent cells. Thus, you will see multiple uncapped cells occurring in lines or patterns across the face of the comb. But, I digress …
The feeding behavior of both moths results in, you guessed it, feces! The larvae will defecate in cells containing developing bees. The images you provided show feces that are quite small, leading me to deduce that it was a younger caterpillar feeding on the wax in that cell. Do not worry though; they are not there to eat your bees, just the wax around them. The average colony is able to keep wax moth damage to a minimum. For more information on wax moths, see: https://edis.ifas.ufl.edu/in1108, https://edis.ifas.ufl.edu/aa141, and https://www.tandfonline.com/doi/abs/10.3896/IBRA.188.8.131.52. Hope these help!
Q Strange flight behavior around the hive
I have LOTS of bees around my hive, going in and out through the entrance and also trying to get into the back of the hive. The bees act unusually agitated and flying around the hive more than they do if they were just coming and going with foraging. I am wondering what is going on? Is that normal behaving? Is it a good sign? Could this mean my hive got robbed by another colony? Are they fighting?
(For the benefit of the reader: Matthias supplied a video showing heavy flight activity at the nest entrance and bees trying to get into a crack in the back of the hive. There was also some bee interest at other cracks in the hive, though they only seemed to be able to go into/out of the main entrance, and possibly the opening at the back of the hive. There also appeared to be a few dead bees around the nest entrance.)
There are a couple of possible answers here. I will start with the one I hope it is first, as this would be better for you (and your colony) than the alternative. First, it could be a simple case of orientation behavior. In this case, a group of bees may have finally reached their foraging age and are taking orientation flights for the first time. If this is orientation behavior, the erratic flight activity should last about 5-30 minutes. What is orientation behavior? It is what worker bees do as they transition from inside-the-hive tasks to outside-the-hive tasks. Remember, they have never left the colony before and they need to learn where home is in order to find it successfully when returning from future foraging trips. While orienting, they will fly away from the hive, hover facing it, and then land on the hive entrance. They will repeat the process over and over for 5 minutes or more. Orientation flights are interesting because they seem to occur in specific windows of time (i.e., they tend not to be spread out throughout the day but rather happen in a tighter window), when the weather is favorable for flight. Thus, you will see hundreds of bees doing it at the same time. It can be alarming to behold and usually leads the beekeeper to think their colony is swarming, or something worse. Nevertheless, it is a natural part of what bees do as they transition to the field labor force. Think about it as flight school for pilots who will soon be allowed to go out on their own.
Ok, now for the bad option. It could also be robbing behavior, where this hive is weak and unable to fend off bees from other hives that are trying to steal its resources. What makes me worried that it is robbing behavior? First, I see some dead bees under the bottom board toward the front of the hive. They may have died fighting to defend their hive from the bees hovering around the nest entrance. Also, I see bees trying to get into the back of the hive, near the juncture between the bottom board and brood chamber. Keep in mind that there is usually fighting when bees are robbing. That could explain the dead bees under the front entrance. Also, robbing bees often try to get into the hive in areas that are not the entrance. Seeing bees trying to get into the back of the hive makes me a little anxious.
At the end of the day, you should not be worried if it is orientation behavior. This is normal. If it is robbing behavior on the other hand, you will need to t