Monday, April 21, 2014

Racing Ahead...

Visited the Savernake Forest area with Pete Eeles today, to check on larval progress.  The news is that they are romping ahead, and are currently even more advanced than they were at this time in 2011 - a ridiculously early year in which the adults started to emerge in mid June.  Do Not Panic yet, as the jet stream's just jumped south and the larvae should get held up by rain, but watch this space: you may need to bring your annual Emperoring holidays forward - warn the boss...

Today, two out of 18 larvae had just changed into the 4th instar.  This is quite the earliest I've recorded 4th instar larvae in the wild in five years' recording.  Here's the proof, it's No. 213 -

Note the old skin just beneath him, and the new, large horns.

In 2011, another very early year, they changed into the 4th instar in late April.  Usually 4th instar larvae appear in early May.  Last year, after a late spring, 4th instar larvae didn't appear before mid May.

Several were skin changing today, like this one, No. 111 -

Also, the one below will change skin soon, it's No. 198 -

Conversely, three haven't started feeding yet, which is not unusual at this time of year (none had commenced feeding this time last year).  This includes No. 151 who had to be pet-rescued - his sallow tree was felled during the winter, he survived but the tree isn't coming into leaf...

Unfortunately, three larvae which Pete and I had followed closely since last September have recently died, shrivelled up, desiccated.  This happens quite frequently in captivity in late winter / early spring but I've only recorded three wild larvae succumbing in the previous four years.  Please stand in silence and weep copiously for No. 40 - 

Finally, in case you make the horrendous mistake of underestimating the strength and durability of caterpillar silk, here is one of last September's Purple Emperor larval feeding leaves found still attached to its tree in Savernake today, by silk, having survived the winter's gales -

Whatever mistakes you make in life Do Not Underestimate A Caterpillar (Erucam Nunquam Minoris Aestomate).  No. 198, featured above, had crawled ca 4.5m from his hibernation place to where he is feeding now - bad for someone 1cm long, though I have recorded them move as far as 6m post-hibernation.

1 comment:

irisscientist said...

Matthew. Are you sure you mean 5th instar? As I am sure you are aware the 5th larval instar is their last and considering some of these larvae have recently just emerged from diapause, this would mean that these larvae would be due to pupate in around 2 weeks time? From looking at your pictures I would predict more like 4th instar. There are however no size markers for comparison (only immature Sallow leaves). Mark