Expansion of iris in the north

This map is the work of Martin Partridge, the Yorkshire chair. The data was provided by Stephen Mathers, Ken Orpe, and Richard Jeffery.

South Derbyshire became purple for the first time in 2024, with more squares recorded in the south in 2025, and, particularly, several new sightings in the north-east of the county this year: the latter sightings are not very far from the established localities in Sherwood Forest. 

The Yorkshire sightings are very exciting: all of them except one from the coast near Scarborough [2024]  are from 2025. The map indicates how widespread these sightings were over this huge county, suggesting that they were not the result of releases. 

Leicestershire, Lincolnshire, and Nottinghamshire remain strongholds. 

1st Instar Failure...

Although Empresses dispersed far and wide this season, and laid a vast number of eggs, a great many of the resultant larvae perished early in their journey through caterpillarhood.

Yes, you did read that word, caterpillarhood. Please help it blossom into the English language.

We are finding an unprecedentedly high number of what we call 'L1 Fails'; 

i.e. leaves bearing the tell-tale signs of 1st instar PE larvae, but no 'pillar - the small but distinctive silk seat pad on a leaf tip, plus the characteristic eating marks either side of a midrib isthmus; and if you want to be absolutely certain, the shiny remains of an egg case base close by. 

This is what L1 Fails look like - 

I'd accept either of those leaves as 100% iris, even from a new locality or county (the bottom one also has a gall imitating a Puss moth egg, for fun). 

However, if you want to be 110% sure, then find the egg case base (ECB for short, though that also stands for England & Wales Cricket Board). Here's a shiny ECB just to the right of the midrib, above early 1st instar eating and seat pad (an 'Early L1 Fail') -

In Savernake, where ca 150 egg lay sprays have been found, in the region of two-thirds to three-quarters of the young larvae perished - either to predation or excessive heat. The record is ten L1 Fails on one sallow there!

Most seem to have failed in the first instar, but some failed early in the second instar (and a few eggs failed, either through being sucked by predatory invertebrates or by desiccation). 

I doubt that predation was particularly high this July & August, not least because social wasp populations crashed in mid-July - but this is only speculation, we do not know.

In other heatwaves years, notably 1976 and 2018, many L1 larvae perished. 

The good news is that there is still a large number of larvae around, and that they are relatively easy to find. 

Now that the autumn rains have arrived with a vengeance (just like they did in '76...), the chances of any second brood individuals appearing in the wild are receding fast.  

Here's a deceased Early L1 larva (photo per colleague Gary) - 

Here's a deceased Early L2 larva. It had either desiccated in the July heat or been sucked by a predatory invertebrate - 

Onward, knowing that all things are for the best with this the best of all possible butterflies!

 

Monumental Celebrations

Our government - i.e. the Knepp Wildland Purple Emperor population - has decreed that monuments should be erected or repurposed throughout the land in celebration of the 2025 Purple Emperor season. To this effect, what was once known as the Albert Memorial, a nineteenth century excrescence somewhere in London, has now been rededicated as The 2025 Iris Memorial -