Ancistrocerus trifasciatus Larvae

Apologies, I have no idea what species these are at the moment. I have a little 'bee hotel' in the back garden. I've not seen anything going in and out of it but after taking off the roof, I noticed that something had indeed been in, laid offspring and left. I don't know if all of these belong to the same species but are at different stages of development.
The larvae encased in the silk was at the back of the nest, so if this is the most mature 'tenant' - how will it get out when it reaches maturity.

This was originally 3 images but thanks to the wonder of Photoshop (of which I'm a complete novice) I found it stupidly easy to stitch the images together making them they look like 1! Very impressed with the software.

comments (7)

Ferdy Christant

Lion

This is really cool! We must get to the bottom of this, I'll see if I can get help to ID this. Posted 8 years ago

Pudding4brains

Lion

Howdy, I've seen this before in a short talk for a study group of Hymenopterists. If I would have to hazard a guess it would be toward something Megachilidae-ish but I thought it better to just ask the people that known best instead ;o) Will let you know if any suggestions come in. Cheers, Arp
Maybe also see:
https://en.wikipedia.org/wiki/Osmia_bicornis#Nest_structure Posted 8 years ago, modified 8 years ago
1. Ferdy Christant
  
  Lion
  
  Thanks so much for asking around! Posted 8 years ago
2. Stuart
  
  Lion
  
  Thank you for this - very interesting! My partner said that she had seen one of these flying around the nest but it's entirely possible this insect used one of the nests areas that I cannot access.
  
  The insect she saw was similar in appearance to this:
  http://www.natureconservationimaging.com/images/Ancistrocerus-trifasciatus.jpg
  Posted 8 years ago
3. 1. Pudding4brains
    
    Lion
    
    Yes indeed - I stand corrected. Not the brood of a Mason Bee but of a Mason Wasp (Eumeninae). I received helpful replies from Erik v.d. Spek and from Pieter van Breugel, the latter authored the excellent book "Gasten van bijenhotels" (Guests of bee hotels) found here:
    http://www.bestuivers.nl/publicaties/gasten-van-bijenhotels
    It's Dutch language, but he specifically linked to this chapter, with ample info on the Mason Wasps:
    http://www.bestuivers.nl/Portals/5/Publicaties/Bijengasten_Tweede_druk/Gasten%20van%20bijenhotels_H17_HERDRUK.pdf
    Last things first: All larvae would complete their development and rest as a "resting larva" as seen in the cocoons on the right until it's time to pupate and complete their cycle, often overwintering until next spring. Then, the "younger" ones at the front of the corridor will simply leave first.
    The analysis that these should be from a Mason Wasp is based on the thinly silked cocoons and on the fact that the brood cells are filled with larvae of other insects (as food for the larva of the wasp). The type of prey is partially diagnostic in that some genera will mostly use caterpillars of small Lepidopterans and others will use grubs of Curculionidae or larvae of Chrysomelidae etc. Pieter thinks that he sees Chrysomelid larvae and I think they might rather be small caterpilars. So, he lands on Symmorphus sp. but if the prey is caterpillars the Ancistrocerus you linked (if that ID is correct?!?) might be a better fit.
    Imho, there are a few things you might do to get closer to the truth:
    - Remove the prey from the first brood cells and see what it really is (Lepi/Coleo?)
    - Try to let the resting larvae in the last cells complete their cycle and see what comes out.
    Cheers, Arp
    
    P.S. Do you have an image of the closing "lid" on the outside of the corridor? Is it straight or bulging out?
    
    Posted 8 years ago, modified 8 years ago
  2. 1. Stuart
      
      Lion
      
      Thank you so much for the really helpful and interesting info above! Would you also please thank Erik and Pieter for their assistance too? I'm very impressed and will take a look at that publication and see if I can get a translated version as it sounds rather interesting.
      
      In terms of the linked Ancistrocerus image - I was purely going off what my partner described as 'a wasp that was black and yellow rather than yellow and black' and to be honest, I have noticed wasps that match the appearance of the image I posted around the bee hotel but not paid any attention to them (oops!).
      
      The closing lid of the outside corridor is just a straight wall with no bulging out. In fact, it's appearance is exactly the same as the walls on the brood cells if that helps?
      
      I'll leave the creatures as they are - I don't want to disturb them or cause them any damage/disadvantage. Perhaps I'll be lucky and see something come out at some point in the future. The image below is the same bee hotel that I have in the garden, as you can see, it has removable layers but the very top layer under the roof is not removable - I also have something that's living in there too and it looks like it's the same nest structure.
      
      http://nurturing-nature.co.uk/wp-content/uploads/2017/03/A-full-bee-hotel.-But-full-of-what-Nurturing-Nature.jpg
      
      Thanks again :) Posted 8 years ago