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A Two Part Tale Of The Exotic (Part2)

The big story of 2014, which is still developing, is the emergence of gorganus (Continental subspecies) Swallowtails on British soil, following an influx of these magnificent insects during the summer of 2013. The discovery of resultant larvae and pupae in Sussex gardens and further afield has been well documented ('Supplement Three to A Complete History of the Butterflies and Moths of Sussex', Pratt (2014); 'The Sussex Butterfly Report 2013', Colvin et al. (2014); UK Butterflies website) and we waited with bated breath to see if gorganus would emerge in Sussex for the first time since 1948; it did!

So far this year, Continental Swallowtails have been seen in Hampshire and along the Kent and East Sussex coasts, but most of the observations have focused on 9 pupae being monitored in a Chichester (West Sussex) garden, about half of which have now flown the coop, bringing the total of known adult specimens on the wing to about 10. In order to honour the privacy of the owners, access to these insects has been very restricted, leaving them tantalisingly out of reach. But common sense dictates that these butterflies must represent just 'the tip of the iceberg', and many more must be present in Southern England.

Yesterday afternoon (29th May) I made my third visit to a very promising looking area of semi-urban 'wasteland' (with a public right of way running across it), close to the superstores on the outskirts of Chichester. This was one of several areas around Chichester which I had earmarked using satellite imagery and then followed up on foot, confirming an abundance of food-plants in suitable habitat.

As with the Long-tailed Blues last year, it is a great feeling when a hunch (and a lot of groundwork) pays off, so I was positively euphoric when I spotted this giant within ten minutes of arriving, just as the sun started to break through the cloud. At present I have no way of knowing, and perhaps never will, whether this is one of the insects which has emerged from the monitored garden, which lies just over 1 Km away. My gut feeling is that it isn't, and that more will appear here and elsewhere.

Fantastic stuff Neil!
Once your antennae get twitching, there really is no hiding place for even the rarest of insects is there? .
You have honed your fieldcraft and observational skills to truly awesome levels over the past few years and are deservedly reaping the ultimate rewards.
Well done that man!

Trev

Trev:

Fantastic stuff Neil!
Once your antennae get twitching, there really is no hiding place for even the rarest of insects is there? .
You have honed your fieldcraft and observational skills to truly awesome levels over the past few years and are deservedly reaping the ultimate rewards.

Concur entirely.

Am I right in thinking that gorganus is routinely double (or even triple) brooded? Our own Fenland race usually has just one generation each year with only a small second brood. So when might we expect the offspring of these British gorganus to be flying?

Jack

Superb find - really well done! And fantastic photos to boot!

Cheers,

- Pete

A brilliant piece of work, Neil .
This is right up there with your Littlehampton Large Tortoiseshell, Mill Hill "polonus" and Chichester Queen of Spain(s). Superb images too, which do justice to the find

Great stuff!

Vince

Well done!

Thanks Trev, Jack, Pete, Vince and Susie. I'm still up here on Cloud Nine, sitting next to Pete and his McSkipper/SPBF combo.

Jack: I suspect that gorganus manages to fit in a third brood further south based on an earlier start. I would guess that Guy started seeing this subspecies at the start of April, giving just enough time to potentially go thrice before the season draws to a close. However, the emergence period for Swallowtail seems quite protracted, so I guess many later individuals would fall into the bivoltine category. Given that most of the British gorganus seem to be following an approximately britannicus timetable, I suspect their progeny (assuming they get to meet the opposite sex!) will be late July and August butterflies, with larvae again pupating just in time for winter (we hope!).

BWs, Neil

I've prepared some humble pie, just in case I need to eat it! I was quite sure gorganus couldn't gain a foothold in the UK, on the grounds that if it could, it would have done so long ago.

Yes, this year gorganus was flying at the end of March in North Italy and early April in Switzerland. Last year my latest record (Switzerland) was 25th September. Voltinism is difficult to judge in a species with such altitudinal range - especially as this one is so fond of hilltopping - but I suspect, as you suggest Neil, that the latest ones are the grandchildren, not the children, of the earliest. You never can be sure - Apollos span May-September but are emphatically single-brooded.

Are there any known mating barriers between gorganus and britannicus?

Guy

Hi Guy,

I think it's very premature to even bake Humble Pie just yet, as this 'event' may yet fizzle out. There is a historical precedent for gorganus periodically setting up home in the South of England along the Downs between Dorset and Kent, but populations have always (so far) been knocked out due (allegedly) to poor weather years. However, I do think gorganus has a better chance of getting both feet through the door than Queen of Spain.

"Are there any known mating barriers between gorganus and britannicus?". That's a very interesting question, and one that I certainly don't have an answer to. I suspect that a butterfly breeder somewhere has tried to pair them, but I believe it's difficult enough to get some species to pair at the best of times, so I'm not sure whether the knowledge is out there.

BWs, Neil

Neil,

Incredible photos - I am on awe of your zen-like ability to locate and photograph rare butterflies, just fantastic! Those orchids aren't half bad either

BWs

William

Neil , What a find I bet your really pleased and your photo's are great Goldie

Every UK Butterflyer is following this fascinating and interesting development, its so reassuring that we have the right man in the right place...yet again...very well done Neil cloud nine is a wonderful place!!!

Bill

"When in doubt...venture out"

Thanks William, Goldie and Bill.
By way of an update - I spoke to Michael Blencowe today, who informed me that, as yet, only 3 out of 9 pupae in the monitored Chichester garden have emerged (not 4/5 as I thought). That suggests there is still plenty of time for numbers to increase significantly in the coastal counties. Action stations!
BWs, Neil

Tremendous sleuthing, Neil and what a reward! Your perseverance and dedication are peerless.

I can only agree with the above comments, Neil and also offer my congratulations! What a stunning find (and photos). Superb stuff, Keep us posted....

I will certainly be keeping my eyes open for any Swallowtails on trips between Surrey, Sussex and Kent.

Best wishes,

Lee

Absolute magic Neil!!

Great stuff Neil- well done! Ian

Thanks David, Lee, Bob and Ian. I'm hoping that there'll be enough of these to go around.

I was unaware until this morning but Michael Blencowe and Ralph Hobbs, who have been monitoring the Sussex garden gorganus pupae, have been meticulously photographing the emerging adults. Comparison of wing margin patterns demonstrates beyond any doubt that my Swallowtail is NOT one of their chaps, so almost certainly emerged where I found it.

BWs, Neil

Great stuff Neil and brilliant photos of Gorganus

Mike

Back Down To Earth

Following the excitement of my Chichester gorganus on Thursday (29th May), I've been restricted to much more local activities. It will probably be Tuesday before I can get back west to hunt for more Swallowtails.

However, yesterday (30th May) I did manage to get an hour and a half at Springhead Hill, despite the dull conditions. A search for roosting butterflies confirmed my impressions that Small Blue has still got a long way to go before recovering from the 2012 wash-out. This seems to be one of the species which took a real hammering in Sussex.

The most numerous species I found was Common Blue, including a beautifully marked female perched on a Common Spotted Orchid, of which there are hundreds now appearing in the meadow. I also photographed the humble Small Heath. They don't do themselves any favours by being so hard to approach with a lens!