All about Insects 2020

Well done, will see what I can find out!

Still a bit stumped on this one, have sent your pic to an expert for his help!
Can you rear a couple in captivity til a bit bigger to make ID more easy?

Will do Wendy, I'm struggling to find a suitable container - they were off out of the air holes in the one I had put them in!  

I'm using a moth inspection pot with a coffee filter paper clipped under the top to cover the air holes.  Hope that will be sufficient for gas exchange?  I understand people have used coffee filter paper in homemade face masks, so thought it should be ok.

Behaviour so far:  mass hatching, all very mobile and none seen feeding at all.  Available food is verbena leaves, verbena flowers and lavender flowers. None of the caterpillars are settled on those.  I've also pulled up a tiny grass plant with little roots and put that in there.and I think some look like they're settling on the leaves, but too soon to tell really.

The caterpillars seemed mostly off up to the top of the pot, and they're rearing up, seemingly searching.  

If picked up with a soft paintbrush, they curl up to a tiny dot.  Some fall off on a fine thread.  All of them seem to really want to be off!

Any suggestions as to what other food to try? 

You could try dandelion, nettle, small plantain leaves plus grasses & the host plants too ... any kind of covering with several small pinholes is fine, they don't need a great deal of air whilst so small, don't keep more than a dozen in a pot though, any kind of small plastic kitchen container will do ... it is a habit that they wander from food source & constantly have to be returned, best to provide quite a covering of leaves but be vigilant about removing decaying ones ... a bed of kitchen roll helps with moisture problems & makes it easier to clean out poo! Be watchful as to when they shed skins though as musn't be moved at this time! Good luck

Thanks Wendy! I am certain a see a tiny bit of frass on a grass blade, and a little chew hole. I'll pick a little selection of leaves twice a day.

There are presently way more than a dozen in this little pot so I'll release more of them today.

I used to have a little handheld digital microscope which was perfect for things like this, I got some lovely pics of pond olive nymphs. I have no idea where it is now, but I'm pretty sure I no longer have it - had a massive clear out before some repairs on the house a year or so ago.

I think I will get another one so might be able to get some better images for you and others to see soon. Thanks for the help and advice so far!

Hope you find your microscope but may not be necessary as they grow pretty quickly!

I'm a bit of a geek so it's worth having one - for the next mystery! I hope we can solve this one, it's puzzled me for a year or two but I never caught them hatching before.

Hopefully we'll get a definitive ID as they grow on a bit, still leaning towards Sawfly but would love to know which one ... fellow geek here! Lol

Is this anything like the one you had?
www.amazon.co.uk/.../ref=olp_product_details