I thought to myself "a green caterpillar on cherry - I bet there are lots of species matching that description", and I nearly came to the conclusion that it would be too difficult to try to identify it. I've got less than two years' experience with identifying adult moths, never mind caterpillars. Nevertheless, I picked one of the leaves with the caterpillar on it and took it home. I started to work through the new caterpillar book from Henwood, Sterling and Lewington, using the index by host plant as my starting point.
Sure enough, the book contains forty-two entries (moth species) against Cherries spp, Bird Cherry, Dwarf Cherry and Wild Cherry, although there are two or three duplicates. So I worked my way through these entries, looking up each of them in the textual pages and the plates and eliminating species not matching the description, distribution, season or appearance. I made an initial mistake in thinking the caterpillar was not a looper, so I skipped all of those entries whose ABH code starts with 70 - until the caterpillar started to move and proved me wrong, which was just as well.
Somewhat to my surprise, after a couple of hours I ended up with a single match. I believe that it's a March Moth. It's a good match in appearance - not only to the illustration in the book, but also to photos on ukleps.org, pyrgus.de and elsewhere.
I could be mistaken and it may not be the final instar (especially at this point in the season), but there is one aspect that increases my confidence. The book mentions that in the final instar "there is a pair of vestigial prolegs on A5"; ukleps.org has a similar comment and I don't know whether this implies that in earlier instars the A5 prolegs are fully present or entirely absent: I suspect the latter. My caterpillar was not very cooperative when it came to photography in a bright light, so I only have one usable photo, but at full zoom I think I can just about make out a tiny bump on A5 where the proleg would be (it may be my imagination); otherwise there definitely is only a single pair of full prolegs.
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| March Moth caterpillar, Newton Longville 27th April |
Tim Arnold
Newton Longville, Bucks
Hi Tim, really sorry to have to put a downer on your satisfaction, but I'm pretty sure this is a Winter Moth. At this time of year Winter Moth is the first thing to rule out when looking at green geometers on pretty much any tree species.
ReplyDeleteMarch Moth has a slimmer body, and the spiracles are slightly further above the whitish line along the side (the subspiracular stripe). Also, as you suspected it's a bit early in the year to be seeing March Moth - they might just about be hatching by now but would be fairly tiny I think.