Prospects for the 2025 Purple Emperor Season

A very early start to the 2025 Emperor season is likely - but there's a huge BUT coming up...

At this range, it is possible that 2025 will break the all-time record for the earliest definite Purple Emperor (10th June 1893). The current modern record is 11th June 2017 & 2019. 

Many other butterflies are emerging unprecedentedly early this year.

But here's the BUT, and it's massive: the fine spring weather is forecast to break down over the weekend of May 24th-25th, just when the bulk of this generation of Emperor caterpillars will be pupating. Ouch!

They can get stuck pupating for ages...

and, the longer Emperors spend pupating, or as pupae, the fewer of them make it to adulthood (due to high levels of predation: a student is about to start a thesis on this, I'm helping her).

So, the fate of the 2025 Emperor season hangs in the balance. How long will the (much needed) rainy spell last, and when will the fine weather return? 

Perhaps 2025 will track 1990, when a sublime spring broke into a wet June and early July, before the sun returned - but too late for the Emperor, who only emerged in low numbers.

Now, it is likely that some larvae have already pupated in the warm South East, though a lengthy spell of relatively cool nights will have slowed many other larvae right down.

Larvae I've been following got stuck changing to the final instar, then fed up rapidly to reach Late L5 stage (= ready for pupation). They may get stuck again.

Because of the cool night factor and the forthcoming weather breakdown, I'm forecasting that the first male of 2025 will be seen at 2.30pm on Wed June 11th. (Last year I was out by 22 hours).

However, it may be earlier, and we should be on Purple Alert during the weekend of June 7th-8th, possibly earlier. Note that iris now tends to appear before the White Admiral and S-w Fritillary... 

We have the chance to smash the all-time record... Carpe Diem!

WATCH THIS SPACE, I will update regularly.  

If the weather is clement, adult number could be very high. Fingers crossed...