Burnet moth larvae

Following on from Ian's post yesterday about the narrow-bordered 5-spot burnet moth larva photos and the following discussion, here are a couple of photos of burnet moth larvae taken on Ffos Las in previous years, neither of which are seen on larval food plants - typical!

 

This was taken 2.6.2013

 

 

This was taken on 13.6.2011 and is significantly different in spot pattern.

 

 

This picture of 5-spot burnets was taken on 13.6.2011 and the moth on the left has the pair of spots mid-wing touching whereas the central moth has the 2 mid-wing spots separated.  Are these 2 different species or is it natural variation?  I look forward to finding and photographing the caterpillars and adults in the coming weeks.  My reference books are not giving me much help so any comments or information would be much appreciated.  (I have family commitments for much of half term week, so won't be able to comment or post for a few days.)