Return of the leaf cutter bees

You may remember that last year I had very little success with my solitary bee houses, and was surprised when a leaf cutter bee emerged from one of the old sealed tubes a few weeks ago. I put the lack of nesting last year down to the boxes being sited on my wobbly decking, and this Spring moved the bee houses to a more stable base, and hoped for the best.

And now, just a few weeks after I saw this first bee emerge, I seem to have three species of leaf cutter in my garden. I have never tried to identify my leaf cutters to species before, and it is quite difficult with these little bees. There are seven species of leaf cutter (Megachile) in this country. This site has photographs of all of them, but I’m still dithering over which is which in my garden! However, I am hoping to be able to identify them properly soon, having requested a back copy of British Wildlife Magazine (vol. 10, no. 6), which contains, I’m told, the best guide to leaf cutters currently available. Hopefully when this arrives I’ll be closer to knowing the species of my bees – so long as they can be identified from photographs, rather than via dead specimens and microscopes.

So, let me show you what I’ve seen in the garden so far!

A surprise hatching and an early arrival at the nests:

Above left: My unexpected hatching emerged from a narrow bamboo tube on 20th June, in need of a clean-up. You can read more about this hatching, with photographs, in a previous blog post. Above centre and right: Two days later I saw this bee with pollen all over its face, going in and out of one of the cardboard tubes of the bee house. From its size I would say it was the same bee. It has now been going back and forth into this tube for almost two weeks, carrying pollen on the hairs of the lower half of its abdomen, as can be seen in the right hand photograph. The presence of these hairs is an identifying feature of leaf cutter bees, but also of other types of bee such as the Osmia (see comments). These are the first few pictures I managed to caputure of this bee which is very quick in flight, coming out of the tube like a bullet out of a gun, so they are none too sharp!

After two weeks of observation I have yet to see it enter the tube with a leaf piece, and it is still working away deep in the tube, building up its nest slowly. Hopefully when it is finished I will be able to see what it’s building the cells from. It must be using very small pieces of leaf that I can’t see as it whizzes past. And I have still not captured on camera its front end as it enters the tube. Most of the leafcutters I have ever tried to photograph approach the tubes with great pieces of leaf and fly uncertainly at times, allowing a bumbling photographer a fair crack at a shot. This little bee flies almost straight into the tube!

Update: see pictures below and comments for a probable identification for this little bee as Osmia.

A beauty in the garden:

Above: Two days after I had noticed the small leafcutter had moved into the bee tubes, I spotted this bee on the pink flowers of one of the succulent plants. This is quite obviously a different type of bee, which is much larger and fatter than the one nesting in the tubes. I have seen this bee in the garden now for a couple of weeks, either on this succulent or on the borage flowers, but I have not seen it nesting or collecting leaves for its nest.

Another leafcutter at the bee houses:

Above left: A day or so after I first saw the beautiful fat leaf cutter on the succulents, I saw this similarly-sized bee investigating the bee houses. I only had a brief view of it the first few days. The weather wasn’t particularly good, and it was buzzing around and then flying off before I could even focus on it properly, as you can see. The thorax looked white with either pollen or sawdust from the tubes, so I could not be sure if it was the same bee a little the worse for its travel or an entirely different bee. It took me several days of watching both bees, and some much better photographs to decide that this was most probably a third leaf cutter species.

Above right and far right: The bees have a choice of tube to nest in at the bee houses. There are the cardboard tubes from the Oxford Bee Company (available at Wiggly Wigglers here), bamboo canes and sweet cicely stems of various thicknesses, some bored logs, and a bee block (far right). I’ll give a run-down on which bee has settled into which tube in a later post. You can see how close the bee homes are to my garden chair, which illustrates how safe it is to encourage them to your garden.

A bit of a clear out:

Above: On a sunny morning a few days later, I found the second fat bee clearing out one of the old bamboo canes which had been nested in a previous year. You may wonder why it is that these bees seem to prefer the labour of emptying a tube which has been nested in previously to using a fresh, unused tube, as I do! It is a task of several hours to remove all the old debris from a used tube, when there are what seems perfectly good clear tubes right near by. Above left: here you see her kicking some of the smaller bits of leaf and other debris back behind her onto the floor. The centre pictures show her dragging out a larger piece of old leaf. She flies a few feet from the nest to drop these larger pieces away from the site, but as there are often several pieces together due to the way the nest is constructed, some pieces fall below. This far right photograph shows the curvature of the old leaf pieces which were cut and positioned by a bee in previous years. More on the construction of these nests can be seen in this earlier post.

In the interests of identification, the second from left shot above shows that this bee has dark hairs on the last two segments of her abdomen, which is different from the all golden or yellow hairs on the ‘succulent bee’ above. This is the kind of detail which I am hoping will help me to identify the species when I receive my guide.

Above left: While all this clearing was taking place, the first leafcutter was zipping in and out of the cardboard tube just above this bee’s head. The smaller bee can just be seen poking it’s head out tentatively at one point. Generally speaking leaf cutters, as many other solitary bees including the miner bees, will live side-by-side and seem actually to prefer it to nesting alone, despite their ‘solitary’ name. However, I have noticed the bees having small spats, and I will describe some of these in a later blog post. The picture above left shows quite clearly the considerable difference in size between these two bees, which is one of the things I find difficult to envisage from descriptions in identification guides.

And some exploring – uncertain where to nest?

Above: After excavating the bamboo for quite some time, the bee decided to explore all the other options in the bee house. I don’t know whether she had found some problem with the bamboo, or what reason there was for this, since she eventually went back to finish clearing and start laying in the original place. But here you see her exploring the sweet cicely stems, and the cardboard tubes which were quite a squeeze for this bee, while the smaller leaf cutter can actually turn round inside these tubes. She then got herself covered in sawdust while exploring the drilled logs, and lastly exploring the bee block.

She also flew over the top of the nests several times and all around it, and then flew all around me to make sure I was not a threat. Eventually she began to settle again in her bamboo tube, which is where we will find her in a future post, since this one has become so long.

In the meantime, it’s still not too late to set up some tubes, or build a solitary bee home yourself. It really is worthwhile, since these bees do so many interesting things you can see right up close, and they are very unlikely to sting, and do not swarm or attack – see the bee pages for more information:

| Bee PagesAll about Bee Houses|

Update: Unexpected hatching bee a probable Osmia.

Above: Thanks to Alan who kindly commented on the photographs in this post it seems very likely that this small bee is not a ‘leaf cutter’ but another bee which uses leaves to construct its nest – an Osmia. See the comments for Alan’s ideas on this, in which he describes the way this bee uses leaves to construct its nest. The photographs above seem to confirm this identification. Above left: I managed to retrieve the plug which the first bee had pushed aside in hatching, and on close inspection it does indeed appear to have been made from chewed leaves (centre left). This is supported by the centre right picture, which shows one of these bees entering a tube with a tiny piece of leaf, which is not big enough to seal a tube on its own, and would need ‘stitching’ together in some way. Far right: The end sealing of this year’s nest appears to be of the same construction – chewed leaves.

All images and text ©Christine Farmer Please contact me if you wish to use any of the images.

| Home | About the Artist | Contact | Galleries | WritingNews |

Comments

  1. Alan

    Megachile aren’t the only bees to have pollen collecting hairs under the abdomen, Osmia do also (plus couple of other related genus). The firt series of pics look very Osmia like to me, and if they aren’t collecting cut leaves this also points to Osmia. It’s too late for O. rufa but species such as O. leaiana and O. caerulescens are a possibility. Species such as these build their nest cells with masticated leaves/vegetation so you’ll notice this when the nests are capped off. I’m afraid for a positive identification, as with the majority of bees, specimens are needed under the microscope, even with the Brit Wild key.

  2. Christine Post author

    Thanks, Alan! I was wondering whether you would comment. I have received the British Wildlife key now, and struggling my way through it! I have pictures of the small bee now taking what looks like a small piece of leaf into the tube – it seems to me that she is making almost a patchwork of sealing up the cells, but so hard to tell – and I think she’s finished with the tube now about 1cm from the end, so I can’t see properly what she was doing. The succulent bee I also have lots more pictures of since she’s a regular visitor to the garden. I had wondered if she was one of the Megachile who build in sand or earth, since she hadn’t shown any interest in the tubes. Thanks ever so much for your help!

  3. Christine Post author

    Alan, I’ve updated the post with some more pictures and thoughts on the tiny bee. Thanks again for your help, it’s much appreciated.

  4. Patsye

    Dear Christine
    I am fascinated to read about your leaf cutter bees as only today i found some as i went to pot up my mini cucumber plants. Frightened me it did but then as some of the leaves fell of i realised what they were. The leaves appeared to be hypercium (some in a neighbours garden), although something has been using my rose leaves!(it happens every year). I only found six and put them into some compost so i hope they will be ok. Later on i will make a house from canes. Thanks for an interesting and informative site. Loved the tv shows xx

  5. Christine Post author

    Hello Patricia – thanks for commenting, I’m glad you found the site interesting and a little useful. I think the leafcutters use plant pots quite a lot, as someone wrote to me last year when she found a whole nest in one of her potted plants. I would think they would be fine in new compost, and will need to be somewhere cool and dry over winter, such as a shed. Hopefully they will hatch out next summer and use your bamboo houses. Best of luck with it all. Oh… tv shows?

  6. Simon

    Hi Christine, Thanks for all the effort you put into your site. It helped me find out what type of bee I had the pleasure of hosting under some old patio slabs a couple of years ago. Since then, I have invested in bee houses and really enjoy watching the leafcutters come back and forth. Mine seem to prefer hollow canes in a wide variety of diameter to holes in wood blocks that I also have available to them (Althought the Mason bees from earlier in the year loved the holes in wood blocks).

    Mine have suffered with the attentions of parasitic wasps sneaking into the chambers to lay their own larvae when the leafcutters backs are turned which is a bit distressing to see.

    Interestingly one leafcutter completely cleared out a chamber that had been filled and sealed this year, before it re-did all the work agan so I’m not sure if she realised something had invaded the tube?

    I’ll be interested to know if your back copy of the British Wildlife magazine is informative. Best wishes, SIMON

  7. Christine Post author

    Hello Simon, and thanks for your comment. It’s always really great to hear what successes others are having with their back garden bees! I have found that my leafcutters prefer drilled logs and bamboo canes too. I had never provided drilled logs before, but they are definitely their first choice. I’ll be writing about the logs again soon – always seem to be behind in updating things.

    Sorry to hear about your parasitic wasps. Isn’t it interesting that one bee has completely re-done a tube she’d filled and sealed? As you say, perhaps she realised there was a problem. There is so much to observe and wonder about with these bees. In particular I’m interested in the selection process they use for the leaf pieces. I’ve watched a bee try out several leaves, sometimes cutting part of a disc and then abandoning it, before finally cutting an entire piece and flying back to the nest. What makes them abandon a half-cut leaf? I’ve also seen them fly from leaf to leaf and hold the leaf between their jaws before deciding on a particular specimen. Presumably they are looking for something of particular thickness and perhaps malleability? I have quite a few photographs of this process to post over the coming weeks.

    I think that as a previous comment from Alan stated, it is very difficult to identify the leafcutter to species, even with this British Wildlife guide. The guide is written in a way which isn’t easy (for me?) to follow, and the differences between species are so small that a very good photograph and a trained eye is a must. I can only hope that in posting some newer close-up photographs someone with more specialised knowledge and experience will come along to help. However, I would get a copy of the guide in any case and see how you get on with it – perhaps we can compare notes?!

Leave a Reply

Your email address will not be published. Required fields are marked *