Sunday, September 14, 2014

The Nightmare Continues...

I am about half way through my annual search for Purple Emperor larvae in / around Savernake Forest, Wilts.  This is the 6th year I've done this.  To date I have found only 12, and it looks as though this will be the poorest year I've recorded. 

Part of the problem is the shortage of suitable mid-green, soft, matt foliage.  Far too much of the foliage this season is thick and coarse leaved, which is dark-green or even blue-green in colour.  This results from the early and rapid spring we had.  It seems that late springs produce more suitable foliage for the late summer / autumn larvae. 

I've found an unusually high number of failed breeding sites this season, where the larvae have vanished.  This I attribute primarily to the preponderance of coarse, thick leaves, though the cold, wet August cannot have helped. 

Another problem is extensive damage on previously favoured trees by frog hopper nymphs.  They've trashed many of the best breeding trees, curse and crush them. 

However, here's a healthy larva I found today, changing from 2nd to 3rd instar (a little on the late side) -

1 comment:

Guy said...

My experience this year, after the wettest July and August in living memory, is that the cats revel in the rain. I have dozens of photos of 1st to 3rd instar cats completely submerged and making no attempt to move to drier spots. Leaf-tip raindrops make excellent hideaways - it's almost impossible to see the cats and probably more difficult for bugs to pierce and suck them too. So I suspect it is other factors - like the shortage of suitable foliage - that are contributing to caterpillar loss at Savernake this year. My tally, on my daily lunchtime dog walk, is that of 15 eggs/cats found, I can still locate 9. Two of these seem to be on a different leaf every day and give me serious headaches trying to relocate them. The others have settled down. Three are known to have been taken by insect/arachnid predators. The other three absentees might still be alive - they travel quite some distance in search of good leaves.