bee biology

Hourglass bees: even bees have places they can’t scratch

These bees have white hourglasses stenciled on their thoraces.

Try as they might, honey bee legs don’t reach far enough to groom their entire thorax. So sometimes, an hourglass-shaped blotch of pollen remains.

What looks like an hourglass-shaped paint splotch on the thorax of some bees is actually pollen. In the past, I often saw these stripes — usually in yellow — and wondered what they were. The bees look like they squeezed through someone’s freshly painted woodenware.

But according to Rosanna Mattingly in her fascinating book, Honey-Maker, the design occurs when pollen-covered bees groom. The honey bee uses her two midlegs to clean pollen from her forelegs and the back of her thorax. However, there’s a place she can’t quite reach, right down the middle of her back.

She swipes each side of her thorax, removing the pollen in an arc, much like the sweep of a wiper blade on a car. The hourglass design remains after she’s reached as far as she can on each side.

From the comments below, I learned a word for these unreachable places. According to Wikipedia, the acnestis lies between the shoulders and the lower back of an animal, a place out of reach for scratching (and grooming).

Honey Bee Suite

About Me

I backed my love of bee science with a bachelor’s degree in Agronomic Crops and a master’s in Environmental Studies. I write extensively about bees, including a current column in American Bee Journal and past columns in Two Million Blossoms and Bee Craft. I’ve endured multiple courses in melittology and made extensive identifications of North American bees for iNaturalist and other organizations. My master beekeeper certificate issued from U Montana. I’m also an English nerd. More here.

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  • As a new beekeeper, you can imagine what thoughts I had when I witnessed these stripes on my bees this past fall! First I thought someone else’s colony was invading—thinking someone “painted” those stripes… yeah, right!

    After I posted the question to those at the Vermont Beekeepers Association, I was told a lot of “newbees” have the same concern. It was due to the pollen of the jewelweed, now in bloom!

    (That’s a great photo, too, showing the stripe!)

  • I took your advice for winter reading and got a copy of Rosanna L. Mattingly’s book Honey Maker. It is a really good book and I will recommend it to other beekeeping friends. I also recommend your site, by the way. Many thanks!


  • Thank you, thank you, thank you! I have seen this many times and worried it was a sign of a brewing problem in the hive. You have a knack for adddressing practical beekeeping issues as well as pollinator esoterica!

  • Well, I thinks someone needs to tell those drones to clean “those girls” (sorry) backs while they are just standing around waiting their turn.

  • That area actually has a name. It is called the acnestis. It’s the area that an animal cannot reach on their body. Think about it in terms of cows and cats. Cows have a really large one, but flexible cats probably don’t.

    • Adam,

      I have a question. All the definitions I find for “acnestis” say it is the part of any animal where it can’t reach to scratch; in fact, that is the derivation of the word. Is it used to describe the area where you can’t groom as well? It’s a fine point, I know, but I don’t want to end up using it the wrong way.

      • Scratch, groom, rub, reach… I didn’t really see much of a difference. It doesn’t really matter to me what the animals reason for reaching for that spot, its just the spot that it can’t reach. Maybe it is just for scratching, but it’s still an interesting that somebody would come up with a name for that spot. That was one of the words on “Says Who” on NPR a couple years ago. It just stuck with me.

  • Thank you so much for the picture of the bees with the stripe or hourglass on their thorax and the explanation for it. I have seen my bees coming in and out with it for the past week now and have been trying to find out what it was! Being a new beekeeper, I feared and imagined some interesting possibilities of what it may be. Delighted to find it was none of those. Thanks again

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