Long-tailed Blue ALERT

[bugboy]

Some of the arguments the conspiracy theorists use are quite hysterically ludicrous. The main one that seems to crop up over and over again is that the western immigrants (Sussex, Hampshire etc) can't be natural due to the distance across the channel unlike the Kent ones, suggesting that once they hit the north coast of France they start using road maps to locate the shortest route . As best as i can tell this seems to stem from birders who are perhaps mistakingly comparing butterfly (and by default insect) migration to bird migration. Broadly similar yes, but birds live long enough to learn the route that has the shortest sea crossing and over time these become the main migration routes. Every single LTB that has ever migrated is several generations removed from the last one that made the crossing so there's no mechanism for this to evolve, certainly in the short time that LTB have been coming to the UK in numbers.

The other one is that they turn up in the same places every year . Well of course they do, it's a known hilltopping species, and a hill that also has plenty of foodplant is going to be a magnet for both sexes. And off course once its known to photographers then they'll turn up every year too, ignoring a nearby hill that might also have some every year. Clouded Yellows seem to turn up in the same places year after year too but I don't see the same arguments for their 'miraculous' appearance.

I'm sure there are a few deliberately released individuals every year but with so much empirical evidence available, for those to cast doubt on all the others is it bit like me rearing a few Small White's and then assuming all the Small Whites in the area are mine. In fact far more likely to come across a captive reared Painted Lady in the UK that a LTB.

The main culprits are now so invested in their own opinions being fact, having touted them for several years, that no amount of genuine evidence is ever likely to change their minds.

[Matsukaze]

Some of the arguments the conspiracy theorists use are quite hysterically ludicrous. The main one that seems to crop up over and over again is that the western immigrants (Sussex, Hampshire etc) can't be natural due to the distance across the channel unlike the Kent ones, suggesting that once they hit the north coast of France they start using road maps to locate the shortest route . As best as i can tell this seems to stem from birders who are perhaps mistakingly comparing butterfly (and by default insect) migration to bird migration. Broadly similar yes, but birds live long enough to learn the route that has the shortest sea crossing and over time these become the main migration routes. Every single LTB that has ever migrated is several generations removed from the last one that made the crossing so there's no mechanism for this to evolve, certainly in the short time that LTB have been coming to the UK in numbers.

The other one is that they turn up in the same places every year . Well of course they do, it's a known hilltopping species, and a hill that also has plenty of foodplant is going to be a magnet for both sexes. And off course once its known to photographers then they'll turn up every year too, ignoring a nearby hill that might also have some every year. Clouded Yellows seem to turn up in the same places year after year too but I don't see the same arguments for their 'miraculous' appearance.

I'm sure there are a few deliberately released individuals every year but with so much empirical evidence available, for those to cast doubt on all the others is it bit like me rearing a few Small White's and then assuming all the Small Whites in the area are mine. In fact far more likely to come across a captive reared Painted Lady in the UK that a LTB.

The main culprits are now so invested in their own opinions being fact, having touted them for several years, that no amount of genuine evidence is ever likely to change their minds.

This, plus...

A butterfly flying north that reaches the French coast at, say, Le Havre, may well be more likely to make it to southern England by flying across the Channel at once rather than following the coast - it is probably not going to get predated and, flying over the open sea, has little choice except to keep going until it arrives. A butterfly following the coast has its natural enemies to contend with and can only reach southern England by flying over several hundred miles of potential breeding habitat.

[millerd]

I would add that LTBs can be found in Europe, Africa, south and southeast Asia, in Australia, and even in the Hawaiian islands. To reach some of those places, I suspect it crossed more than 22 miles of water...

Cheers,

Dave

[Neil Hulme]

It is now clear that we're enjoying the largest ever invasion by the Long-tailed Blue. The species has been observed in every coastal county along the South Coast, from Cornwall to Kent. The progeny of an early wave (see below) took another step further inland than usual, being seen in Oxfordshire, Bedfordshire, Essex and Suffolk. With day length and foodplant availability still being favourable, these adults have bred again, providing the first evidence of double-brooding on UK soil.

It will be some time before I get the opportunity to update my personal diary, so in the meantime, here's a summary of what we've observed in Sussex so far, and what is likely to happen (assuming reasonably good weather into late autumn).

First wave arrived 29 June (27 on IOW) into July; progeny mainly emerged 10 Aug - early Sept (locally, a few earlier in East Sussex); earlier adults producing a second UK brood due mid Sept onward (larvae now pupating). The emergent adults are likely to reverse-migrate.

Second wave arrived 15 - 27 August; progeny due late Sept onward. The emergent adults will reverse-migrate.

Third wave arrived 29 August - early/mid Sept (ongoing); progeny due mid Oct onward (well into November). The emergent adults will reverse-migrate if the weather allows. Deterioration of the weather (temps below c.4 degrees) may mean that some individuals will not successfully complete their life-cycle.

The first wave was small, the second very large, and the third probably larger still.

Finally, will there be another 'party on the beach' at Worthing? I believe so, having gained access to the large allotment complex in West Worthing, from whence they almost certainly came last late Sept, I can confirm that the place is positively dripping with eggs, as is much of Sussex.

I know of a private garden where in excess of 100 eggs have been laid, and recently visited a remote beach where I saw a minimum of 17 adults. The numbers are far greater than most people probably realise.

BWs, Neil

[Padfield]

That's fantastic, Neil.

As an observation, I was in Málaga from 1st to 8th April this year and was amazed not to see any long-tailed blues at all until 5th April, at one very localised hilltopping site. If my notes are correct, those were the only ones I saw during the holiday - most unusually. It was exceptionally hot and dry in Spain this year, with drought already setting in in April, and I wonder if the blues had all packed up their bags and headed north to lusher lands, getting a headstart on their usual breeding/migration timetable.

I saw very few Lang's short-tails as well ...

Guy

[David M]

Must admit I have seen precious few Long Tailed Blues on the continent this year. I did see a fair number in Andalusia in May but hardly any in France in late June/mid-July, and single figures in Montes in early August.

As Guy suggests, perhaps they moved north quite early this year given the abnormally hot spring in Iberia and some parts of southern France.

[Neil Hulme]

Thanks, Guy and David. David's earlier comment in this thread ("LTBs have been thin on the ground in the Alps & Pyrenees this last couple of weeks") hadn't worried me regarding my understanding of how events were unfolding, because I suspected that much of the population had already shifted further north than usual, triggered by the spring inferno in southern Europe. I think we now have enough data to be pretty sure that this has happened.

As an aside, yesterday I walked through Broadwater and Worthing Cemetery, to say hello to the great nature writer Richard Jefferies (1848-1887), as I do occasionally; this is also the resting place of the great ornithologist W H Hudson, and it's a wonderfully wild place with some interesting butterflies. A female Long-tailed Blue flew over Jefferies' grave and I tracked her over some distance before she started egg-laying on one of just two very small stands of BLEP in the cemetery. What would Jefferies have made of that?!

BWs, Neil

[Jack Harrison]

Neil: A female Long-tailed Blue flew over Jefferies' grave and I tracked her over some distance before she started egg-laying on one of just two very small stands of BLEP in the cemetery. What would Jefferies have made of that?!

I won't be having an idenifiable grave, just a hole in the ground in a natural burial site in the Cairngorms: no memorial stone.

But for those who do want a stone, instead of all that usual guff (philanthropist, donor, humanitarian, blah, blah, blah), far better might be an inscription:
"I wonder what is going to perch on this stone 200 years after my death?" 
At least someone might actually read that.

Jack

[Allan.W.]

Had an early morning trip to Kingsdown Leas (Kent ). Having seen a couple of entries on line showing a couple of well worn males at the Leas ,and with a bit of time on my hands i decided to go and look for myself . I parked by the Dover patrol monument and started hiking towards Kingsdown Leas ,plenty of BLEP patches in good flower (4-5 different colour forms ) . I spent a good while scanning the Pea clumps with no luck
little paths led to most of these clumps .............so plenty of people have been looking ! reaching the second bench seat ,sat for a drink ,looking over the top of the large bramble ,ivy ,BLEP patch beside the seat ,i noticed a "small" blue flashing around the very tops of the clump ,saw it several times but it wouldn,t settle . Just as i started on my way again a blue flashed high around the brambles ,giving me a fairly good view twice and i,m fairly certain it was a male Long -Tail . Continuing on towards the Golf clubhouse ,and scanning the numerous BLEP ,what i took to be a worn Chalkhill ,settled on a Plantain head about 2 metres in front of me ...............this time no mistake ..........A VERY worn Long-Tail ......i,ve put a couple of shots on ,I think its a female.
Allan.W.

[Allan.W.]

Reading your last post Neil ,reminded me of a similar situation a few years back ,we were over Worthing way and i said to my wife that as we were close by i,d like to pay my respects to those two great country writers .Not knowing the area and having not done our homework we drove around ...........quite aimlessly ,and gave up we couldn,t even find the cemetary.....let alone the graves ! Something that i,m definately going to rectify next year ! Thanks for keeping everyone up to speed on the Long-tails .
Regards Allan.W.

[Jack Harrison]

The professer said that the first thing that struck you after you left the pubic car park was the grafitti in the cemetary 
(I was once guilty of that pubic order offence - on these pages!) 

Jack

[Mark Tutton]

After seeing my first Long-tailed Blue at Beeding Cement works in 2013 I planted some Broad-leaved Everlasting Pea in my garden. I live in Portsmouth on the south coast, so I don’t think it was completely wishful thinking that one day my plants might be graced with a visit from this lovely butterfly.
However, in the intervening years I have scanned the plants religiously in late summer but every visiting blue has been of the holly variety. Last week a LTB was reported a few miles away and I visited the location where it was seen on the off chance but my luck was out.
I have two BLEP plants and the larger one seems to flower in mid summer with very few flowers in late summer when the blues are about, but the other, which is self seeded seems to flower much later and currently has good numbers of flowers and buds.
On returning home, and being in LTB search mode, I decided to have a look for eggs, despite the fact there had been no sign of adults. To my utter amazement I found an egg on the first raceme I looked at! What a sneaky butterfly
In all I found five more eggs, all of which have hatched, so who knows I might have adults in the garden in October?

[David M]

...On returning home, and being in LTB search mode, I decided to have a look for eggs, despite the fact there had been no sign of adults. To my utter amazement I found an egg on the first raceme I looked at! What a sneaky butterfly

In all I found five more eggs, all of which have hatched, so who knows I might have adults in the garden in October?

Great news, Mark. Hopefully you'll get to see at least one freshly-emerged adult next month.

[selbypaul]

How exciting Mark! Plant it and they will come! (With some caveats of course). But fantastic news, I look forward to hearing updates, assuming those pesky Blue Tits don't eat all the caterpillars like they do in my garden!

[David M]

I have a range of aggressive solutions to deal with tits, Paul.

PM me if you need further details.

[Neil Freeman]

In all I found five more eggs, all of which have hatched, so who knows I might have adults in the garden in October?

Great stuff Mark Fingers crossed for a nice fresh LTB in your garden in due course.

I had a look around Emsworth and Thorny Island for BLEP when I was down that way recently but couldn't find any.

Cheers,

Neil

[Neil Hulme]

A further update below, with some projected emergence dates for those interested in tracking down fresh, UK-born individuals. So far, the species has behaved precisely as predicted, so I'm confident that we'll start to see some spectacular action if we get some decent weather this weekend.

The first wave arrived in Sussex from 29 June onward (27 June on IOW) and flew until mid/late July.

Most of their progeny emerged from 10 August onward, although a few early runners emerged at the very end of July at Newhaven. This UK-born brood continued to emerge until the start of September, with the last pristine adults from this cohort being detected in a Felpham (Bognor) garden (1 September), on Eastbourne seafront and in a Lancing garden (2 September).

These adults (some of which shifted northward again – being seen much deeper into Sussex than usual, and across inland counties including Oxfordshire, Bedfordshire, Essex and Suffolk) produced the first-ever confirmed second brood on UK soil, which emerged from 15 September onward (as observed at Newhaven). These second UK brood adults may already be reverse-migrating, although as yet there is no direct evidence for this.

The second wave arrived over the period 15-27 August. Their progeny are due to emerge from late September onward, with a likely start date around 23 September. The emergent adults (which will probably be common and widespread) will reverse-migrate and should again congregate at beach-head exit points such as Worthing (a search of the allotments just 1km further inland from Worthing beach revealed a very large number of eggs on a variety of leguminous plants).

Given the current weather forecast, the settled period from 26 September onward could prove highly productive, at sites almost anywhere along the coast. The exodus of LTBs will continue long into the autumn, as the progeny of the third wave (see below) starts to emerge, although deteriorating weather may ultimately curtail their numbers.

The third wave arrived from 29 August to early September and flew until mid/late September. Primary immigrants (which hit the entire length of the South Coast this year, from Cornwall to Kent) are now dying off rapidly (numbers at the Pagham beach breeding site dropped from a peak of 26 on 11 September to just five on 15 September). The last eggs are now being laid on UK soil by primary immigrants (e.g. Buckle Bypass, Seaford on 16 September).

The progeny of the third wave is due to emerge from mid October onward and probably well into November. The emergent adults will reverse-migrate. Deterioration of the weather (particularly temperatures below c.4 deg C) may mean that some individuals will not successfully complete their life-cycle.

The first wave was small, the second very large, and the third probably larger still.

BWs, Neil

[Old Wolf]

I will eagerly await any reports from over the weekend which will decide when/if I make the journey again this year. Train strikes taking place on the Friday and Saturday are once again at a very inconvenient time for my butterfly adventures this year as Saturday 30th would have been ideal, weather permitting of course.

Once again, many thanks Neil for keeping the updates going for those people like myself who live a long way away from the action

[Bertl]

I have never seen the UK brood of LTB......but I was lucky enough to see what I assume are LTB on a business trip into Baku, Azerbaijan in October 2018.

Photos attached.

Bert.

[Allan.W.]

A female Long -Tail briefly in the Dungeness bird obs garden late morning ,nectaring on the flower pot plants directly below the Large Bladder Senna Shrub ,which hosted an egg laying female 3-4 years back ........................We were ten minutes too late !
Allan.W.