Monodontomerus wasp a parasitoid of red mason bees and its life cycle video

June 7, 2014

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

Monodontomerus wasp. A silent deadly assassin of Red mason bees 

 I designed my solitary bee boxes to allow for detailed observations to be carried out without hindering the bees themselves, allowing me to make this video and more! Bees are in decline and need as much help as we can give them. That means research and I am learning more all the time and now have a nest box that allows me and others to do just that!

What do these wasps look like?

They are very small and very agile and determined to achieve their sole mission in life. To lay eggs and pass their genes onto the next generation… see below.

Monodontomerus wasp ovipositing through mud & inside a Red mason bee cocoon

Monodontomerus wasp ovipositing through mud & inside a Red mason bee cocoon

A video of the life cycle of the Monodontomerus wasp, (Monos) a parasitoid of red mason bees, which I made to share, because many people will never have seen this before. If not checked they can devastate your red mason bee cocoons. Full instructions on how best to manage them come with my award winning  and successful solitary bee nest boxes.

I was asked to give a presentation to BWARS members at their AGM in the World Museum in Liverpool, 2013. For many years I have learnt how to manage and stop Monos killing my Red mason bees. What if I totally disregarded my own management practices, then made a video by actively allowing them access to the inside of my nest boxes and filmed what happened?  So I did and called the presentation, The ‘Design and development of educational wild bee nest boxes allowing for observational studies’.  I got the idea to continue with the life cycle video as a result of it. The filming had several positive and negative repercussions, some of which I had not envisaged.

Monodontomerus wasp larvae Nurturing Nature   Negatives

Loosing perhaps 150+ bee larvae in cocoons.

Time and effort spent rectifying the actual loss, damage limitation and potential loss of more bees.


This experience enabled me to design the nest boxes to give better protection from the wasps.

Rewrite my instructions to give better management control of them for my customers.

I made several informative videos.

I learnt: How devastating they actually are, more about their emergence times, how determined they are to find cocoons, researched how they actually do find them, how successful they can be and much more.

Never to allow Monos into my nest boxes again! Ever!

More knowledge gained about this parasitoid. For example, this wasp is raised and released as a biological control for sawflies that have been accidentally introduced into North America. So if you had an orchard that needed pollinating by Mason bees and it was near a forest. Orchard growers need the Mason bees and foresters need the Monos. A real conflict of industries!

“All my articles and videos, available free, are funded by my  teaching and sales of award winning bumblebee nest boxessolitary bee boxes,  and wormeries. Please help by spreading the word and forwarding this link to your friends and colleagues.  Thank you” George Pilkington

For more information about solitary bees visit BWARS

National Bee Unit (Food & Environment Research Agency) solitary bees info sheet

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.

Interested in Citizen Science and Pollinators, visit the Buzz Club

“All my articles and videos, available free, are funded by my  teaching and sales of award winning bumblebee nest boxessolitary bee boxes,  and wormeries. Please help by spreading the word and forwarding this link to your friends and colleagues.  Thank you” George Pilkington


{ 15 comments… read them below or add one }

Marian June 7, 2014 at 5:34 pm

Horrible George!!
What time of the year are these most active and how can this years cocoons be protected ? Do leaf cutters suffer as well??



nurturingnature June 7, 2014 at 8:30 pm

Hi Marian, will email you. Cheers, George


David Brear June 8, 2014 at 8:00 am

I don’t know, George, you keep producing these amazing videos … They deserve wider publicity surely. Such a major contribution to education! More people should see them.

In the meantime, don’t stop!


nurturingnature June 8, 2014 at 11:23 am

Thanks David. Nice of you to say so!! Hopefully its a drip drip effect re education of these fascinating bees and now people have the knowledge (and nest box!) to do their own observations, studies, research and teaching! Cheers George


Jo June 8, 2014 at 10:02 pm

Hi George – amazing video. I love my red mason bees too! There is a fly that hangs around the bee houses and nips in to the hole when the bee leaves for pollen or mud. I assume they are laying an egg. Any idea what it might be? Thanks, Jo


nurturingnature June 8, 2014 at 11:14 pm

Hi Jo, Thanks for comment. Cacoxenus indagator….will be doing an article on it soon! Cheers George


Jim Cane June 17, 2014 at 11:05 pm

George- brilliant macrovideography…makes anything we might do for an educational video on monos to be superfluous. And as you say, without monitoring and control, they can be devastating for managed solitary bees like the several Osmia species being used (I have 5 species in management and increase here).




nurturingnature June 18, 2014 at 6:52 pm

Hi Jim, Thank you for your very kind comments. Its ever so pleasing to receive such comments especially from a solitary bee researcher of 30 years experience such as yourself and working for the United States Dept of Agriculture. Knowing that you have seen my little video taken at home in my garden and felt you had to comment! I really appreciate that. Thanks again, Kind Regards, George


Ben white August 16, 2015 at 8:19 pm

Hi George , great and informative website , I found a mud hive in my shed with large cocoons , and tiny (2mm) what I now no are wasps ovipositing the cocoons , I was just searching for what type of bee / wasp they were , I have learnt a lot today. thanks for the info


nurturingnature August 17, 2015 at 9:57 pm

My pleasure. Cheers, George


Richard Phillips July 19, 2016 at 12:58 pm

Hello George
Your article is excellent reading and very informative.
This year I made manageable mason bee nest box with 75 chambers 100mm long. These are 5 per row routed 10mm slots,bolted together in a stack.
35 chambers were used fully used and have found 5 chambers that have the wasp larvae in some compartments.
As these are clamped together,is the wasp going in while the bee is making the compartments and laying them?
How do I ensure the Monodontomerus wasp does not invade my chambers?


nurturingnature July 19, 2016 at 10:03 pm

The mono larvae are only inside the cocoon, more likely to be cacoxenus indagator. See if you have any spaghetti type frass in there which will confirm. HTH, Cheers George


Richard Phillips July 20, 2016 at 10:20 am

Yes you are spot on with your inormation they are c­acoxenus indagator larvae.
Thnks for your input George much appreciated.



Richard Phillips October 29, 2016 at 7:20 pm

Hello George
All my Mason and leaf cutter bee’s are tucked away for the winter. Have tried the candling method that is talked about on some videos,but don’t seem be able to see anything. Do I need to bother about this metod or not?


nurturingnature October 29, 2016 at 8:41 pm

Hi Richard, Yes it is worth it. You need a powerful torch and should only keep them on the lens a short time re heating them up. Google it. Cheers, George


Leave a Comment

Previous post:

Next post: