Slowly into Hibernation

iris larvae are going into hibernation in the wild distinctly late this year.  On Tuesday Nov 19th only eight out of 25 larvae checked were in hibernation, though four others were crawling around on stems looking for hibernation places, like this -  

One of the larvae still on leaves was only about 1/3rd coloured up.  Here it is -

In contrast, in 2009, when I had a similar sample size, all were in hibernation by Nov 15th, with the last one being seen on leaves on the 8th. 

The previous latest I've recorded wild larvae on leaves are singletons on 16/11/10 and 14/11/11, but those were atypical retards.  This year I may even find one or two on leaves in December.  Many of the breeding sallows still have green leaves.

The impact of the late spring is still evident.