Can anyone identify these caterpillers or grubs?

[Margaret]

Found these chaps between some layers of landscape fabric stored in an outside box. Hope it's not bad news - there are quite a lot of them

Can anyone ID them please?

[shelagh]

I always work on the rule that if they look nasty they are

[Tim Ingram]

These are swift moth caterpillars which Alan mentions on the Galanthus thread. They are voracious feeders on roots and bulbs in the ground but good food for robins when you discover them in pots! (Along with vine weevil).

[Alan_b]

Very bad news if you have snowdrops - and quite a lot of other things also. See:

http://www.donsgarden.co.uk/pests/538?telephone=5

My most recent mention of these blighters on the forum is here: http://www.srgc.net/forum/index.php?topic=11281.msg290864#msg290864

[Margaret]

Thank you for the ID, Tim. Not good news. Your instincts were right Shelagh but I don't understand why the blighters were in a box containing stacks of empty pots and heavy duty landscape fabric. They have eaten holes in the fabric but there are no plants in the box and the larvae seem very healthy. Also I can't find a photo on google showing that sort of felted quilting which they are emerging from (or living in?).

I bagged them up and took them to the plot to feed to the robin but there was a mini riot and so they are back home and in the freezer for a few days.

Alan, I have been following your troubles with swift moths and googled them not knowing I was supporting a significant population. I have a few snowdrops and will be vigilant. Many thanks.

[johnralphcarpenter]

Who was rioting, the bugs, the robins or the other plot holders??

[Margaret]

The robins are quite vocal but it was the plot holders who weren't happy.

[Alan_b]

Swift Moth larvae even had a brief mention in the RHS publication 'The Garden' last year.  If I remember correctly, the writer found that they demolished a peony.  But they remain obscure as garden pests and a.f.a.i.k. nobody makes a specific nematode.  If you want to redeem yourself with your fellow allotment holders you could do worse than follow the advice I recently found here https://apps.rhs.org.uk/advicesearch/profile.aspx?PID=506 

* When applying for these parasites it is advisable to send to the firm samples of the pest(s) on their host plants in a dry polythene bag in a crush-proof container to ensure that they are species that can be dealt with by the parasites.

and thus send them off to a nematode 'manufacturer' in the hopes of getting something that is known to work.

[Anthony Darby]

Don't understand why swift moth caterpillars would be in landscape fabric.

[Maggi Young]

Their Mother got caught short .... of just caught.......?

[Anthony Darby]

They look more like the larvae of Aphomia sociella, although this moth is associated with bumble bee nests.

[Margaret]

I was worried about that, Anthony and sent an email to the Natural Science Museum to double check the ID.  Got the reply below this afternoon.

Our ref: IAS 2014-0084
 
Dear Ms Turner,
 
Thank you for sending the photos.
 
You have the larvae of a Bee Moth Aphomia sociella (family Pyralidae). The caterpillars of these micro moths live inside bumblebee or wasp nests, dig tunnels and spin tubes of very tough silk, and also produce a waxy substance.
 
For more information on these fascinating moths and their life cycle please follow the links below and read the info sheet attached to this email.
http://www.naturespot.org.uk/species/bee-moth
http://www.discoverlife.org/mp/20q?search=Aphomia+sociella&guide=Moth&cl=US/TN/Carter/Roan_Mountain
 
I hope you will find this information useful. Please send us more photos of interesting or unusual animals you may find in the UK.
 
Yours truly,
 
Florin

I'm very relieved not to have a large colony of swift moths   What a wonderful service from the Natural History Museum. I'm going to remember them next time I fine something unusual.

Alan, thanks for the advice. I try to use biological control where possible but it only seems to work on greenhouse crops. They are a friendly lot at the plot - I don't think they were going to lynch me

[Margaret]

Yes, you're right, Anthony

[Tim Ingram]

Well you learn something new every day! They must be remarkably similar to swift moth caterpillars. I would imagine that the latter might occur in allotments (especially when sometimes overgrown) without allotment holders knowing. We have had serious problems with swift moth caterpillars in potted hellebores to the extent of treating them with imidacloprid.

[Alan_b]

I think the head of the swift moth larva may be more strongly marked but they are remarkably similar.  That's a lucky escape - you really don't want to find swift moth larvae.  I grow quite a few bulbs in pots, including expensive snowdrops.  Sometimes I've found larvae instead of the bulbs that were there the previous year.