bee biology

How the honey bee makes pollen pellets

Outside-of-hindleg

A honey bee has three sets of legs, and each set is different. The last two legs—the hindlegs—are designed to compress and carry the pollen pellets that are characteristic of honey bees and bumble bees.

We’ve all seen those hard round nuggets in various colors and sizes, but did you ever wonder how the bees pack the pollen into a ball? Well, the secret tool is called a pollen press. The pollen press is actually made of two flat plates that are hinged together. One plate is on the distal end of the tibia, while the other is on an adjacent segment called the basitarsus.

If you lined all the leg parts end to end, starting at the thorax you would see:

coxa→trochanter→femur→tibia→tarsus→pretarsus
However, the tarsus is further divided into several sub-segments: the basitarsus and four small tarsomeres.

What I have shown below is the joint between the tibia and the basitarsus, because that joint is the pollen press.

Squeezing pollen like toothpaste

When the joint is bent, the plates pull apart and the bee stuffs the opening with pollen that she collects from her body. First, she uses all six legs to scrape the pollen into one place: the inside of the hindleg basitarsus. Then she combs it off the basitarsus with stiff bristles on the edge of the pollen press called a pollen rake. She cleans the left with the right and the right with the left, until the open press is full of pollen.

When she straightens her leg, the plates close against the pollen and force it up into the pollen basket. It’s like a tube of toothpaste: when you squeeze the two sides together, the paste comes out the top. Here, when the two plates are squeezed together, the pollen is forced up into the pollen basket. Although it may seem backward, the pollen basket is actually filled from the bottom.

Every time the bee grooms the pollen from her body, she works the pollen down to the inside of the basitarsus of the rear legs and then into the press before she gives it another squeeze. Is that cool or what?

The leg part shown below was taken from a dead honey bee I found in my driveway. She had one of those cards that said, in case of her death, she was leaving her body to science. RIP.

Rusty
HoneyBeeSuite

Inside-of-hindleg

The inside of a hindleg. When the joint is open, the pollen press can be filled by raking the pollen off the opposite leg. © Rusty Burlew.

Outside-of-hindleg

The outside of a hindleg. You can see the indentation where the compressed pollen will accumulate, called a tibial corbicula or “pollen basket.” © Rusty Burlew.

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17 Comments

    • Scott,

      That’s a new one on me. I know they collect propolis in their pollen baskets, but I didn’t know about beeswax.

    • Hallo Scott, i don’t know how to reach you to ask if I can use your photo with the bee with wax in her corbicula when I do the translation of what Rusty had written about pollen baskets. I am not on facebook and don’t want to be. So I need to appoach you differently. Apologies to Rusty for this detour.

  • Thank you Rusty, your posts give me more information about bees I did not fined it any where. I ask for permission to translate to my language Arabic.

    Thank you

  • I’m still laughing about the card carrying bee. Of course she would. You make me a happier beekeeper. Thank you.

  • This sent me on a little search, because I never think of anything other than pollen or propolis being carried in the corbicular, but in Ecology of Natural History of Tropical bees by David Roubik he states, ” [bees] also carry unusual materials such as feces, mud, cerumen or wax”. Thanks Scott for opening this issue up.

  • Thanks for this explanation! I assume they reverse the process to put the pollen into the honeycomb back at the hive?

    • Margaret,

      The honey bees back into a cell and knock the pellets off with their feet. Then they turn around and push them in further with their head.

  • I give permission to anyone to share any of my photos as they please. No need to link but I wouldn’t mind credit.

  • Hi Rusty,

    As always great article, we discussed this on our latest podcast.

    One of readers Scott, also shared a pic of his bees with wax in his pollen sack. Not sure if the same Scott that commented here 🙂

    Hope you don’t mind the mention on the show.

    Gary and Margaret

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