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The Architecture of a Bald-faced Hornet Nest

11-29-17 hornet nest 049A8063The exterior of a Bald-faced Hornet nest consists of an outer envelope of paper that is made up of a myriad of horizonal stripes of chewed up wood fibers that have been mixed with hornet saliva. Each stripe represents a single hornet’s contribution. The different colors represent different sources of wood. This outer envelope is only one of several (up to 12 or more) that serve to insulate the innermost, active part of the nest.

Inside these outer sheets are three or four horizontal tiers of hexagonal cells in which eggs are laid and brood are raised. Access from one level to another is at the periphery of the tiers, just inside the shell. The queen begins the nest, building a few cells and raising female workers that then take over the cell-building while the queen continues to lay eggs. As the number of hornets increases, so does the number of cells they build, and as a result the tiers become wider and wider. When space runs out, the hornets remove one or more of the innermost layers of insulating paper that form the envelope, while constructing new sheets on the outside. The nest continues to grow in this fashion until the queen’s egg-laying slows down at the end of the season.

The construction of these tiers of cells takes place upside down in total darkness, which is, in itself, quite a feat. When they are constructing a cell, the hornets keep one antenna inside the cell and the other on the outside. By monitoring the distance between the two antennae tips they can judge thickness of the wall. They do a similar thing with their mandibles, with one on each side of the wall, in order to straighten the cell walls and squeeze the pulp flat to remove water.

If the cells were built sideways or upwards they would require constant attention from the hornets until they dried in order to prevent them from sagging. Given that the cells are downward-facing, one might wonder why the hornet larvae don’t fall out. Water has a great affinity for uncoated paper (think of paper towels sucking up water against the pull of gravity). Because the larvae are damp, they actually stick to the paper cell walls. When they are ready to pupate, they must separate from the walls. They do this by attaching themselves to the cell with silk and then spin a silk cocoon.

In order to fully appreciate the intricate architecture of a Bald-faced Hornet nest, you must dissect one (they are only used for one season). Just be sure to wait until there have been a number of hard frosts, in order to assure that there are no residents. (Photo: Bald-faced Hornet nest – (left) envelope consisting of 12 layers & (right) cluster of cells it surrounded; inset:  dissected inner section showing four tiers of cells)

25 responses

  1. Rob Anderegg

    This fall I dug up a ground hornet nest and was surprised to find a very similar structure underground. Not only were they increasing the number of cells and surrounding the entire nest with a paper covering, but they were apparently increasing the size of the hole they live in at the same time, to accommodate the bigger nest.

    November 29, 2017 at 7:45 am

    • I have never heard of them increasing the size of the cavity!

      November 29, 2017 at 8:22 am

  2. Alice Pratt

    Mary, you explained that so well! Amazingly industrious and clever insects…..nasty stings, though.

    November 29, 2017 at 7:58 am

  3. Hi Mary,

    I’m writing to ask for your permission to share portions of this information, giving credit to you, about Bald-faced Hornets Nests via a Facebook page “Acton WildAware”. I will not post anything from this until I hear from you whether or not this is possible. We had a very visible nest on one of our conservation lands and residents may be interested in learning more.

    Sincerely,

    Paula Goodwin

    >

    November 29, 2017 at 8:25 am

    • By all means, Paula. If you can include my blog address, that would be great! Feel free to use photos as well as text.

      November 29, 2017 at 9:43 am

  4. Bill On The Hill...

    Fascinating story on the bald face hornets nest Mary… Thee bee itself is quite a handsome bee as well, at the same time, I have no desire to be stung by one! I have some nice close-up shots of this hornet raiding my hummer feeders a couple years back now. I found their nest way up in a tall skinny maple, top of my d/way, maybe 60ft. up, with it’s bottom ripped wide open from what I believe was blue jays having a meal…
    Great post once again Mary,
    Bill Farr @ WGF Studio53…

    November 29, 2017 at 8:58 am

  5. Bob Brooks

    Thanks Mary. I once had the amazing experience of watching a nest being built from scratch as it was built on one of my windows. I watched every day as the nest increased in size and watched as the hornets scraped the wood from my building and masticate before installation. It gets me crazy when people spray or suffocate these miraculous creatures. I am convinced that they get to know me as I have never been stung even though I have had nests in close proximity over the years.

    November 29, 2017 at 9:16 am

    • Fascinating to get to watch the inner workings in a nest!

      November 29, 2017 at 9:42 am

    • Alice Pratt

      I feel the same way about the multitude of Honey Bees who find their way from “somewhere” to enjoy the many different pollen sources in my yard…I pass very close to them….they are busy gathering…we don’t bother each-other. I admire their hard work & take so many photos…they don’t seem to mind.

      November 29, 2017 at 4:30 pm

    • Alice Pratt

      See my comment after Mary’s, below….

      November 29, 2017 at 5:13 pm

  6. Hello Mary, Thanks for your informative blog everyday. I was out this morning in central Vermont and I saw the biggest “stinky cat” with my dog. It was totally white on the top with black just on its underbelly and legs. I at first thought it was a pile of snow and then possibly a badger but as I got closer and saw it’s tail it was definitely a skunk.
    My question regards the winter coat of the skunk, is it common for them to become white (lose their black) and much fluffier during the winter?

    November 29, 2017 at 9:23 am

    • Hi Bill,
      While skunks do shed their coats and grow in new ones every spring and fall, the coloration of the coat, to my knowledge, does not change.

      November 29, 2017 at 9:42 am

  7. Remarkable work isn’t it. I enjoyed this very much and the comments too. You never stop learning.

    November 29, 2017 at 9:40 am

  8. Jack Cadwell

    This is a great article. I never knew that the hornets re-used inner layers as the nest grew.

    I am always on the look out for these nests around my house, in order to avoid them. I have noticed that hornets always leave room between nests. I have never see two of the same species with 75 feet of each other, except on opposite sides of a house. How do they communicate to keep their distance?

    November 29, 2017 at 10:28 am

    • Pheromones would be my guess, Jack.

      November 29, 2017 at 10:39 am

  9. Juliet Jacobson

    so amazing! humans are schleppers in comparison!

    >

    November 29, 2017 at 10:37 am

  10. Judy Copa

    Hi Mary, We had a big nest on the north side of our barn this year and I am wondering if we leave it there, will the hornets avoid building close to that location next summer? Loving your blog. Thank you.

    November 29, 2017 at 1:51 pm

  11. Kathryn

    A beautiful piece of construction. We’ve had a large one with us for over 0 years. Besides being pretty dusty, it looks just like it did the day I found it.

    November 29, 2017 at 2:50 pm

  12. Kathryn

    The above post should say 30 years, not zero. Oooops.

    November 29, 2017 at 2:55 pm

  13. dp

    Also incredibly strong — several times I stomped the same tier into the mud outside our barn, and it kept popping back up.

    November 29, 2017 at 6:09 pm

  14. lanny moldauer

    Wonderful, incredible story, very lucidly explained and in all the detail one could want. Pix are also terrific. Thank you, Mary.

    November 29, 2017 at 10:41 pm

  15. David Fedor-Cunningham

    Did anybody else notice fewer hornets last summer? I saw a fraction of what I normally see, also fewer wasps. I’ve watched them collect caterpillars in the garden and flies in mid flight, shows the diversity of prey they go after.

    November 30, 2017 at 7:47 am

  16. Guy Stoye

    Great illustration and explanation of these hornets. They and the yellow jackets, unlike paper wasps, are quite defensive and have little toleration for being disturbed.
    The paper wasps (Polistes) are not only the least aggressive but are great for preying on garden pests.

    November 30, 2017 at 2:05 pm

  17. Bonnie MacLeod

    We have a very large bald-faced hornet nest in a tree in front of our house about 30′ up. It withstood the devasting windstorm that took down so many trees and power lines in our area just over a month ago. Swaying to and fro, but not coming down, another amazing feature of the architecture. How is it attached?

    December 6, 2017 at 9:06 am

    • Hi Bonnie! They “papier-mache” it right onto the branches!

      December 6, 2017 at 10:24 am

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