Larva Query

Looking through a batch of photos, taken in June 2010, I came across a few of this cracking larva. The images were untitled and after a bit of searching around, I think it is probably Light Knot-grass. Anyone have any better ideas?

The photo was apparently taken just after one of my raven counts, so the habitat is moorland and is very close to a site, at which I have trapped adult Light Knot-grass a couple of times.