Leafcutter bee larva killed by Coelioxys bee larva using mandible film

June 11, 2015

in A selection of my garden wildlife videos, Gardening For Wildlife, Leafcutter bees, Solitary Bee Observation Box

Which cleptoparasite killed the leafcutter bee larva?

Around this particular nest box, used by leafcutter bees, I filmed 7 different solitary bee parasites. There are several suspects that killed the bee larva, though some can be eliminated from the investigation!

leafcutter cleptoparasite larva Nurturing Nature

Monodontomerus wasps, Pteromalus wasps, Chaetodactylus osmiae pollen mites and Cacoxenus indagator fly are all not guilty! I watched a female Coelioxys cuckoo bee enter this cavity and marked where the cell was she entered on the glass viewing window.

Coelioxys bee about to enter a leafcutter bee cell 2 Nurturing Nature

I was lucky with my timings as when I opened this cell it was pure good luck to find the formidable mandibles of the Coelioxys cuckoo bee larvae. It hatches before its host and is ‘unarmed’  feeding on the pollen nectar mix.

Coelioxys bee about to enter a leafcutter bee cell Nurturing Nature

As it develops through its larval stages, The Journal of Apicultural Research states that it grows a strong mandible, which it uses to crush the egg, or kill its host or other Coelioxys larvae in the same cell. You can clearly see the fang like mandibles in the video. It can open them very wide which is useful when searching for its victim(s) in the dark.

The gruesome looking mandibles drop off after the ‘deed’ is done as they would prove almost useless when eating the nectar/pollen mixture. It therefore gets rid of the evidence! The lava becomes ‘unarmed’ once again, finishing its development inside the leafcutter bee cell. A leafcutter bee larva mandibles could not be used to kill another larva. They are better equipped to eat and drink the pollen/nectar mix, which contains much more fluid nectar than that of a red mason bee cell.

You may find this popular article about leafcutter bees interesting

A great visual guide for the identification of British Coelioxys Bees by the Amateur Entomological Society can be downloaded here

For more information on the above named species go to Bees Wasps and Ants Recording Society  BWARS

For info and link to buy an excellent book Field Guide to the Bees of Great Britain and Ireland by Steven Falk

An extremely useful resource supports this book by a special web site feature within Steve Falk’s Flickr web site which furnishes extra photos and other useful resources to assist with identification.

Filmed using my award winning solitary bee observation nest box which made the film possible

{ 9 comments… read them below or add one }

Theresa July 16, 2015 at 11:27 am

Hi, I have found a cigar shaped “nest” about 6 inches long , stuck up underneath my garden parasol. Half of it fell down when I opened the umbrella and I have had to take the other bit down . Will the bee return to it if I just put it in a box underneath the umbrella or what shall I do with it ? Put it in the shed or something ? Does it need to hang upside down ?


nurturingnature July 16, 2015 at 7:48 pm

Aw shame! She will not find them now. Keep it level if possible and try not to move it too much as the eggs/larvae are very delicate. Keep in a warm place out of sun.Then leave them there! If they are still alive contact me in October for more info! HTH George


Anna September 20, 2015 at 5:31 pm

Hi I bought a red mason bee nest box, it looks like the mason bee hasn’t had a good year but I have evidence of a leafcutter Bee and living larvae. I need to remove them so I can reuse the tubes nxt year. There are also nectar packages along with larvae. I have placed them in a small tin together with nectar, will they find their way to it? These may seem silly questions but I’m not all clued up on bees at the moment. Thanks


nurturingnature September 20, 2015 at 10:01 pm

Anna, I have seen your photos. Leave the bees inside the paper tubes and do not open any more cells exposing the larvae. Put them in a mouse proof container inside an outdoor shed etc then contact me in the spring. HTH Cheers, George Ps You need a much better bee home!


Joseph Priest June 11, 2016 at 3:49 pm

I have a bee house and have 7 off sealed tubed. However today i have noticed 2 of them seem to have been opened. Do any solitary bees hatch the same year as sealed up. Or has some predatory pest opened them up to get at the larva.

Many thanks


nurturingnature June 11, 2016 at 6:42 pm

Hi Joseph, difficult to say, as I have had several over the years and the small hole has usually been in the middle of the mud wall and the larvae have been fine in some cases and predates in others. I don’t know the design of your box which may make it difficult to see into the tubes….I can see in all of mine which helps 😊


Alyson July 22, 2016 at 3:45 pm

Hi, I have a fairly young bird of paradise plant which I recently put outside to get some summer sun. Then today I noticed a leaf cutter bee taking leaves into a hole she’d burrowed into the soil in the pot. As this is an indoor plant sooner or later it should come back indoors but I don’t want to have the bees hatching out indoors. I think the plant will be ok in the greenhouse over winter but will this be ok for the bees? When do they normally hatch out by the way? Thanks for your help. Alyson


nurturingnature July 26, 2016 at 7:31 am

The bees wont hatch until next year so hopefully the green house should be fine. Cheers, George


Alan February 27, 2017 at 12:58 am

Hi George
I have several leaf cutter bees in my nest box this year. Is there anything I can do to help them hatch successfully. I know with Mason Bees people harvest the cocoons, but what about leafcutters?


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