The Purple Emperor Rescues England

Watched the first half of England v DRC. Decided the cause was lost, so went out Emperoring on bike, listening to the match on the radio.

Both England's goals were set up by the Purple Emperor butterfly. Both goals resulted from magnificent 'tumbledowns' (mated female rejecting a wont-take-no-for-an-answer male). Here's Kane's winning goal -

Interestingly, there are still a fair number of fresh-looking males around at Knepp, and males are still 'sallow searching' (for females and female pupae).  

 

Tues June 30th: Apatura iris in cop

Briefly, as I'm too tired. A pair joined at 4.05pm on the shady leeward side of a feeder oak, just 25' up, after meeting in flight. No courtship (he didn't even ask her name...).

They remained together, motionless, wings closed, for a marathon 4 hours and 2 minutes. The average duration prior to this observation was 3 hours 42 mins, from a sample of 19 pairings (now 20). Gentlemen of England, Ladies even, we are outdone, by a butterfly...

We managed to show them off - and a lot more - to one of Knepp's famous Purple Emperor Safaris (estab. 2014) - 

All previous pairings I've seen have been in the tops of tall trees. Really good to see them so low down.  At one point I saw 6 males and 2 females in a vista by that feeder tree.

Onward!

 

 

Mon June 29th: Knepp Transect Data

The Purple Emperor is now at peak at Knepp. 

Today, I walked the Knepp PE transect. This runs down 2km of oak-lined green lane and takes around 2 hrs 30 mins to walk. Weather conditions were Good, with Emperors nicely active (a wind sprung up towards the end - Knepp is a surprisingly windy place).

I totalled 38, including 5 females. 

That's about par, suggesting that the butterfly is in average numbers at Knepp this year (though way down on last year's stupendous showing, which produced a record individual transect count of 80!). 

However, if another extreme heatwave comes over, they'll shoot over early (as happened last year, and in 1976) - in which case this year will become a below average year...

At last, some of Knepp's oaks are producing sap runs. Both males and female cluster around these 'feeder trees', which means they tend to disappear elsewhere. 

Here's some feeder tree action from 2025 -

  

Sun June 28th: The Wind Returns...

Far too windy at Knepp today, again, after a quiet and productive day yesterday. Most of the male territories were unoccupied today, windswept. There was, though, some good activity out of the wind, along east-facing and north-facing edges.

Elsewhere, the Emperor seems to be having a good year in Lincolnshire. Down south, numbers seem at best moderate, but we can't get a reading when it's either stultifyingly hot or blowing a gale...

Here's the wrong Emperor, the Emperor dragonfly, eating a Marbled White - 

 

Sat June 27th: Muggy, Still & Cloudy

Change in the weather, to warm, muggy cloud, with hardly a breath of wind. Perfect Emperoring weather! They love it, and are fully active.

Back at Knepp, after a week elsewhere. People had struggled to see PEs at Knepp during the heatwave, but that changed today: most of the favoured male territories were occupied, with males sailing around joyously, and some females evident. 

Three 'tumbledowns' were seen: descending spiralling flights with "Hi! I'm Andrew Tate" males circling around an "I'm washing my hair tonight" mated female. At the last second she will do a U-turn, hoping that he will crash land and smash up his top range performance motor. This behaviour was first observed by KJ Willmott at Bookham in 1983 - Heslop never saw it, nor me till Knepp. It's common at Knepp during the second half of the flight season.

Here's a female basking in a sloe bush yesterday -

And here's a more typical view of a female (again, yesterday): they spend hours sulking in sallows, all but out of view - 

Today, though, Sunday 28th, the wind has returned. Leeward, leeward and leeward...

June 25th

This time 50 years ago, during the midsummer heatwave that immortalised the Long Hot Summer of 1976, the first Emperor of the year was seen on Midsummer Day, June 24th, by KJ Willmott, at Bookham Common. That equalled what was then the known earliest PE record (the Marlborough College record of 10/6/1893 had not come to light). The following day, June 25th, the first was seen in Alice Holt Forest. Then the Emperor erupted...

Right now, males and the first females are emerging nicely at most sites. In particular, this is the week to look for males feeding on the rides: watch out for the shark's fin wing shape, especially on or around any form of dung.  

In hot weather, and especially in bright sunlight, they tend to feed with their wings tightly closed, opening up only if they crawl into shade. However, you can persuade them to open up by slowly casting your shadow over them IF they are fully absorbed in feeding - watch for the probing yellow tongue and the rocking head. If they take off, freeze - play musical statues. Be careful not to make footfall vibrations, to which they are very sensitive.  

Note that they often take a break whilst feeding, flying up into a nearby bush to clean their tongue for several minutes before descending again. Watch out for the second coming...

Nationally, they'll probably stop descending to feed on the rides shortly after the coming weekend - only males aged 1-4 days do it, plus the odd female in extreme weather.

They should move on to the sap runs soon, to get plastered...

Back to Bernwood 25th June 2026

 At least 4 male emperors found throughout a four hour trial by heat with temperatures reaching 36F.Late morning I flushed a male from dog poo which flew up about four feet to sit for twenty minutes on a shaded blackthorn leaf before descending for another fifteen minute feed on the dog poo.It then flew back into the blackthorn and perched again for twenty minutes on a shaded leaf this time no more than three feet above the ground.Conjecture I know but maybe it did this because if it went to the top of the oaks it would be too hot?