Spring of 2026

Purple Emperor larvae are continuing to develop ahead of any accepted norms... 

They got held up a bit by a cool and showery week in mid-April, but are set to romp ahead this week, under a strong anticyclone.

Over the weekend of April 18th-19th, 49 larvae were checked in Savernake Forest. Of these, two had recently changed to the 4th instar (L4), but the majority were changing skin. That's early, but not unprecedentedly so. 

Crucially, the sallow foliage is shooting ahead, and caterpillars tend to be in sync with their foliage (White-letter Hairstreak larvae are developing apace).

PE Larvae can race through the 4th instar, in fair weather, though they then take much longer in the 5th and final instar - and they can get stuck at red traffic lights (or a full motorway closure) at any stage, in wet weather. 

Here's an Early L4 larva -

Here's an L3 larva about to shed the skin its worn since last September, and has wintered in. Note the hunched position - 

In late April, Purple Emperor larval feeding 'damage' is fairly distinctive. They feed only at leaf edges, and do not make holes (that's moth feeding). The only thing you can confuse PE feeding with at this time of year is the feeding of the common Willow Nematine sawfly Euura viduata -

The 'record' for the earliest wild 5th instar PE larvae is May 1st (2011). That record is under serious threat this year. 

I repeat that PE larvae have come through the winter remarkably well, and that 2026 has the makings of an astoundingly good Purple Emperor year - unless the weather misbehaves.

Also, again and yet again, this butterfly could be on the wing exceptionally early this year.

Watch this space...  We are living through very exciting times...