This weekend I checked 3 wild larvae in & around Savernake Forest, N Wilts (I found an extra one that was last seen in November - Lord knows where it had hibernated as I looked for it three times during the winter). All 3 were mid way through the final instar. They need a few more days feeding before they're able to pupate - and progress in this wet weather will be painfully slow... .
The butterfly is highly unlikely to emerge here before early July (unless the second half of June is seriously good). But iris emerges later in N Wilts than in some other parts of its range, and it may well be that some larvae in Surrey & Sussex pupated before the weather collapsed at the start of flaming June - so the butterfly may appear there in late June. Last year, the butterfly appeared in Surrey two weeks before it started at Savernake.
Meanwhile, back at the ranch, 2 of my captive larvae started to pupate today and the others look fully fed and ready to go down. They seem to be a little ahead of their wild counterparts (but I put a rain hood over the sleeve in really wet weather).
Here's one taking a near-final meal -
And here are my kittens, Wizzy and her partner in crime Matilda -
Plug: The July issue of BBC Wildlife magazine (out now) has a feature on Iris by me. Hope you like it...