More Larval Development News

Yesterday, May 7th, Dave Law found a Purple Emperor larva which had just changed into its fifth and final instar, in Bentley Wood, Wilts. That's very early, though I've recorded L5 larvae in the wild as early as May 1st (Knepp Wildland, 2011). Normally, larvae enter the fifth instar (L5) between May 10th and 20th.  

In Savernake Forest on Bank Holiday Monday, all seven larvae I saw were in the 4th instar, L4. Four were in mid-L4 stage, three were in early L4 (just changed skin).  

What this means is that, despite the recent cold spell, the Purple Emperor is still likely to be on the wing unusually early - perhaps around June 7th. It's wet foliage that stops them, not cold, and the recent cold spell has been a cold drought.  

They are likely to put on a big spurt as another anticyclone is set to come over this weekend.  

I'll make my final prediction for D Day (or rather P Day) in just over a week's time, once I know when they're going to pupate (last year I was 20 hours out...).

Here's some pics from Monday -

This one has just changed to L4. The cast skin, which it's worn since Sept, is to the side. They don't eat it.

Here's one resting, unusually, on the stem. 

Spot the caterpillar! 

For the record, I have now seen this butterfly in the wild, in its various life stages, for 120 consecutive months - i.e. ten years (I last suffered an Emperor-less month back in May 2009). If you're thinking of taking this record on, seek medical help...