Friday 19 September 2014

Why Solitary Bees are Such Amazing Pollinators:

Leafcutter bee on Ragwort
The relationship between bees and flowering plants goes back to the early Cetaceous period, and different species of bee have, over 100 million years or so, developed a number of different physiological adaptations and behavioural traits to enable them to collect pollen.

Pollen carried by honeybees and bumblebees is visibly quite obvious. Both have become extremely adept at packing their pollen loads carefully, and neatly, into the smooth, widened pollen baskets (corbicula) situated on the sides of their hind legs. Once the pollen is packed in, very little is likely to fall off - and what does fall off is not viable anyway. With these bees, it is the pollen that sticks to their body hair that helps pollinate flowering plants.

Solitary bees are less fastidious. They collect pollen on 'scopa'; stiff, branched hairs, located on their legs, under their abdomens, or along the sides of their bodies. 

As the female solitary bee collects pollen, she packs it onto her scopa less carefully, and without the addition of saliva to moisten it. This means it is far more likely to fall off when the bee visits the next flower....which in turn means the next flower is more likely to be pollinated. 

Added to this, some solitary bees carry less pollen in each load, so they need to make many more trips back and forth from the flowers to their nests than do honeybees and bumblebees. These extra foraging trips mean that many more flowers get pollinated in the process.

Perhaps the easiest way to explain the difference between bees' various pollen collecting apparatus, is with photographs….  

Bombus terrestris (Buff-tailed bee) on Buddleia
Bumblebees and honeybees can carry up to 50% of their weight in pollen! 

You can see from this photograph of a Buff-Tailed worker bumblebee, how neatly she has packed the pollen, which she has moistened with saliva, into her pollen baskets. Honeybees do the same.

Most of this pollen will make its way back to the nest, where it will provide developing larvae with the protein they need to grow.

Halictus rubicundus female
Most ground nesting solitary bees collect pollen on scopa situated on their back legs, or along the sides of their abdomens 

This image shows the pollen collecting hairs of the ground nesting bee 'Halictus rubicundus' BEFORE pollen collection. Note how hairy her legs are. 

This is another photograph of the same bee, H. rubicundus. This time her leg scopa are laden with pollen which she is about to take into her nest beneath the ground. 

A large amount of this bee's pollen load will never make it back to her nest as it will have been lost as she visited other flowers en route.

Most cavity nesting solitary bees, like the Leafcutter bee pictured here, collect pollen on their abdominal scopa. This method of collecting pollen is extremely messy and is one of the reasons why some Mason bees (close relatives of the leafcutter) are around 100 times more efficient as pollinators than honeybees.

So, there you have it. Solitary bees are in fact the unsung heroes of the pollinating world!

N.B. There are a few solitary bees that, unusually, carry pollen back to their nests in their crops.

Bumblebees and honeybees are, of course, also wonderful pollinators, but in different ways and for different reasons. More about this another day….


  1. Fascinating info Brigit, thanks for sharing x

    1. Thank you for reading Sandie. I've added a wee bit more info since first publishing it x

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    1. Hello Brigit,
      Just finding your blog posts so interesting......thank you.
      I've just read this in Australian Geographic. Let me know if you can link to this, if not I'll email the article. All about the Blue-Banded. Hope you're having a wonderful weekend.

    2. That was a great little read and I feel a little more learned as a result :)

    3. Many thanks for your feedback Austin. I'm so glad you found it interesting :)

  3. Lovely to know you're enjoying my posts Anita; thank you for your kind feedback. Amazingly, one of my friends sent me a link to the Nat Geographic article about the Blue banded bee yesterday afternoon! Makes me want to visit Australia :) x

    1. You have to visit Australia Brigit!!! So many wild places left to explore!!! If you ever come this way, I know a fabulous eco bed and breakfast in West Gippsland I can highly recommend....ha ha!!! My husband and I travelled through the UK in May and are completely in love with England......all over again!! We're returning in September 2015 and plan to walk through Dartmoor and many other gorgeous places.
      So glad you enjoyed the article. I'll keep my eye out for more and send them your way. Hope the weekend is travelling well for you. Cheers xx Anita p.s. something to tempt you in our direction

  4. I enjoy reading your blog and love your native bee photos.

  5. Hello, I am an Educator with the Grosse Ile nature and Land Conservancy in Grosse Ile, MI. I am putting together a program on native pollinators and how to attract them to gardens. You have fantastic photos of these pollinators - would I have permission to use them in my presentation? I would of course credit them. Thank you for your work in pollinator education!

    Natalie Cypher

    1. Hello Natalie, yes of course, I'm very happy for you to use my photos in your presentation. Thank you for asking me.

      I hope you pick up this reply.... I'm never quite sure if people receive my replies or not.


  6. Thanks! I did get the response forwarded to me email. I really appreciate it!

  7. Wonderful. Thank you for letting me know Natalie!