Catapillers

Thanks for the suggestion, walnut. This latest week of frost seems to have done for the ******s so there are none left for me to photo. I did find one live pieris brassicae lava, now squished, but there was no possibility of misidentifying that, having distinctive markings.

I may have been mistaken about the identification of the small white. The lava were pure green and smooth. It now looks to me that the pieris rapae have yellow longitudinal stripes and are a bit furry, neither of which I recall observing, although the features are subtle and I may have simply overlooked them.
[media]http://en.wikipedia.org/wiki/File:Pieris.rapae.caterpillar.jpg[/media]

On deeper delving there is a possibility that they may have been plutella xylostella