To update, iris is starting to finish at many sites, particularly those supporting small populations. The exceptions will be 'late' sites like Savernake, which should have a good week left, and the mega population at Knepp, which will finish by next weekend.
At Knepp, adults are becoming increasingly worn, torn and localised, and hard to find. A lot of people new to the site are struggling to find them.
Advise: search the downwind side of oaks close to sallow thickets during the afternoon (and warm sunny evenings) only. At this stage in the season both sexes tend to take mornings off - and so would you if you were an ageing rock star, like Himself. If you want something to do during the morning at Knepp then search along the outgrown sloe hedges for Brown Hairstreak, the males of which are well out there and visit Creeping Thistle and Fleabane flowers.
Numbers-wise, Harry Drew and I counted 10 iris on the Purple Emperor transect at Knepp yesterday (Fri 14th), compared to 25 on Fri July 7th and 36 the previous week, when the butterfly was at peak. Many were in very poor condition, though that doesn't stop them behaving abominably. The transect runs for about 2km down a green lane which contains many favoured male territories (we only count Emperors on it, no riff-raff).
I don't think last Tuesday's steady rain, which produced 25mm (an inch) at Knepp, did any real harm to the Emperors - it fell steadily and was not accompanied by the strong winds that really knock out roosting Emperors. It did, though, greatly reduce Purple Hairstreak numbers, which have been astronomical at Knepp this season.
In fact, the weather has been decidedly clement this Emperor season, which means that the egg lay should be good (not least because the butterfly emerged in synchrony with the appropriate growth stage of sallow foliage, which doesn't always happen - never mind what that is, but it's very important).
This female flopped into a sallow close to us late on Friday afternoon, on what was probably her final flight -
Finally, if you want the ultimate quality Emperoring experience, and the opportunity to learn a considerable amount about the butterfly, then please come on one of the Purple Emperor Safaris that Neil and I run at Knepp in season. Next year we will be running afternoon safaris during some weekdays and some day-long safaris at weekends, and can offer experiences like this -
Don't worry about the bloke in the kilt: that's Harry, him's from Devon...
Credit: Tony Rogers, Knepp July 2017