After reviewing the list of biology books in my last post, Mike Riter of New York had a good question about the angle of honeycomb cells.
Do any of those books tell us how much of a tilt, in degrees, the honey bees build their cells so honey won’t leak out as they cap them? I can’t find this anywhere. Seems 40-50 years ago every honey bee article I read had the answer. So what happened? Did we go from everybody knowing to nobody knowing? Did they once think they were all at the same angle and now think they build them with some degrees of difference?
I mentioned this measurement several years ago in a post called, “Why honey doesn’t run out of the comb.” The reason for slanting cells is obvious. Nectar is about as thick as water and would easily flow out of a horizontal cell. Even brood food and larvae could slide out and drop through the hive with a splat if the cells weren’t properly tipped.
Is there a standard angle of cell tilt?
In my previous post, I used the numbers I found in The Beekeeper’s Handbook. On page 19 the authors write: “The cells of the honeycomb do not lie on a completely horizontal plane: the openings are slanted slightly upward by 9–13 degrees. This prevents stored materials and brood from spilling or rolling out of the cells before they are capped with wax.”
But since Mike asked the question, I widened my search. In The Biology of the Honey Bee (p. 81), Mark Winston says, “Unlike most other social insects, honey bees build their cells horizontally rather than hanging vertically, although they are angled up at about 13° from base to opening to prevent honey from running out.”
In Honey Bee Biology and Beekeeping, Caron and Connor mention the phenomenon but don’t quantify it (p. 78): “Bees build the beeswax combs progressively downward, sloping the cell walls slightly upward.”
The final book where I found a reference was The ABC & XYZ of Bee Culture. A diagram on page 177 shows the upward tilt from both sides of the comb midline. The caption reads as follows: “Diagram showing the slight angle (~17°) upward the opening a typical cell has from the midrib.” As far as I can see, there is no further mention in the text.
Leaving the books, I went online. Wikipedia says, “The cells slope slightly upwards, between 9 and 14°, towards the open ends.” That sounds like The Beekeeper’s Handbook, although they don’t reference it.
Causes for variation may be genetic or practical
Altogether, these sources give quite a bit of latitude: 9 to 17 degrees. I suspect that the variation may be due to differences in genetics as much as anything. My husband suggested that the angle might be influenced by the tip of the entire hive, especially when foundation is used. If the foundation is not vertical, the bees would have to build a really sloped cell (at least on one side) to keep the nectar from running out. This is purely conjecture, of course, but it makes sense in a practical sort of way.
Brush your bees up, not down
And speaking of practicality, whenever I’m writing about angled cells I like to remind beekeepers how to brush bees from a frame. If you brush bees downward while the cells are angled upward, the bees’ legs can easily get caught on the cell rims and be ripped off or damaged. Knowledgeable beekeepers brush bees from a frame by flicking the brush up, not down. Not only are the bees less likely to be injured, but they’re easier to get off the frames.
Rusty
Honey Bee Suite
Rusty, Thanks for the comprehensive research above on the angle of honeycomb cells so honey won’t leak out.
It would seem obvious that the upward slope is to prevent the honey from leaking, but is this a correct assumption? Check this study: https://link.springer.com/article/10.1007/s13592-020-00807-9
As beekeepers, we know what bees do but are often in the dark as to why they do it!
Peter Shaw, Sweden
As I must be a bit masochistic I actually tried to read that article. I wound up skimming it pretty good, and having a new appreciation for the clarity of Rusty’s writing. I did understand it enough to appreciate that once again it’s amazing how much I ‘know’ that isn’t even true. Also, maybe I missed something, but did they establish that the brood in the inverted comb hatched out as useful and productive bees?
The 9-13 degree pitch is probably as close as it is going to get. Especially as you are trying to measure a non-constant. In my way of thinking, there may be variables in the tilt of the individual cells caused by any number of things. Temperature would be my number one variation and I believe it might even be possible to measure the tilt on one frame say, early in the morning, then remeasure it at midday on a hot summer’s day and come up with two different measurements due to the wax warming and slumping. Could it be bees in tropical locations build cells at the top end of the tilt scale and bees from colder regions have minimal cell tilt?
Age of the comb, temperature, intended use of the cells built, genetics and the wax forming ability of the individual colony might all have influence on the final measurement.
Then there is the actual measuring. How was it done? Under a microscope? Comparing many hundreds of samples from many hundreds of colonies? Or, judged by old-time keepers with a child’s math class protractor?
For me, they tilt up and that is good enough. How much they tilt to the nearest degree, well that is for the bees to worry about.
Anyone measured one of those “flow hive” frames to see what they decided was the ideal pitch for their plastic cells?
Jeff,
Good idea! Can someone out there with a Flow hive measure the angle and let us know?
Rather late reply but still relevant I think. I have some brand new Flow Frames waiting to go on my hive so I could easily measure the angle without getting sticky.
Cedar and Stuart have tilted the cells at 9 degrees. I’ll send a photo to you Rusty.
Rusty, thanks for the information on cell angle and the reminder about proper bee brushing. Another year is about to pass, thanks again for all your posts. They are really appreciated.
Chris,
Likewise, I appreciate your continued support. Thank you so much and best wishes for the New Year.
The book: The Hive and the Honey Bee says on page 472, between 9 and 14 degrees. (Chapter 14 originally written by Charles C Dadant) just thought I would throw that out there. This book, as you know, is the text book for the masters level of the three part series of the Master Beekeeping courses from the University of Montana. Lots of information in this book.
Ken
Thanks, Ken. I was pretty sure that info was in there, but I couldn’t find it when I was writing the post.
Since honeybees seem to do a lot of things in their hive that are relative to the world outside the hive – waggle dance in relation to pollen/sun location etc – would it stand to reason that they might angle the cells in relation to the ground? If the comb is not perfectly perpendicular to the ground, they would have to adjust the pitch accordingly to ensure that the nectar doesn’t flow out. Granted, when you reuse foundation, this may change, but also may help to explain why sometimes they just don’t like seemingly “good” foundation and rebuild….
Caitlin,
Just guessing, but I think gravity plays a major role in how they structure their combs.
I was wondering if in warmer climates, where the nectar and drying honey are less viscous and more easily flow, maybe more tilt is used.
The thing is, even 15 degrees won’t keep a nearly full cell from draining, would it? How do bees deal with that? Partially capping and starting the cap at the bottom of the cell?
Jim,
I’ve never heard that the angle changes with climate, but part of the reason it works has to do with all the enzymes the bees add to the nectar which, I believe, changes its consistency.
Great discussion! I was wondering if latitude and hemisphere may have a correlation to the tilt/pitch. That would also correlate roughly to temperature so it may be hard to pinpoint.
Sounds like a good university research project – maybe even a world wide collaborative project.