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This one seems quite small, can you give an idea of its size?
Not so small, length is 30 mm.
As to the plant it is Eupatorium cannabinum (Hemp-agrimony).
I had a bit of a look through ukleps earlier Martin and the one which I viewed which I thought looked a bit like it was Scalloped Hazel, it isnt necessarily it but close relatives might be worth a look.
It also looks like http://www.ispot.org.uk/node/83731 and some of the prolegs are very small.
I am not sure your cat is a Scalloped Hazel after looking at some more images. I actually have to go now very shortly and edit an ob. of mine which contains Scalloped Hazel larvae and I thought they were Engrailed.
I'm just not sure of yours, I dont see the small jutting out structure just above the posterior end on yours which seems to be present on all examples in ukleps. I do believe I have viewed a very good likeness for yours in ukleps but I cant remember just now what it was.........
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