Delighted to report that none of the nine larvae I've been following in the wild was lost to predation during March. That is quite an achievement given that predation levels (seemingly by tits) are highest during the late winter period. So far I have lost only two out of 11 larvae this whole winter, though winter is far from over and larvae will be late to commence feeding this year. In other winter's two-thirds of larvae have been lost of predation.
This winter, tit numbers appear to be down, presumably due to poor breeding success in last spring's rotten weather.
Although it's still early days I am minded to revise my prediction for this year's adult emergence upwards - though so much depends on weather during the pupal period and, especially, the flight season. So, finger's crossed, this butterfly may well be on the up again.
It is far too early to predict when the butterfly will be flying this year. That depends on weather during May (larval growth season) and June (pupal period). The fact that spring is late is irrelevant at this stage (iris larvae tend to do very little before the end of April anyway), though the sallows are likely to come into leaf late.