White-letter Hairstreak and elms

[Matsukaze]

Elms are in flower here at the moment, and it is a good time to take note of where they might be and return later in the year to look for the White-letter Hairstreak - the adults will congregate around tall trees in the neighbourhood of the elms.

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Wych elms - the caterpillars should already be out and nibbling away on the flowers, but at only a couple of millimetres long will be very hard to find!

[wavelea1]

Mat

Keep us informed if you come across any caterpillars - the WLH is still a target species for me.

Mike

[Denise]

Mat

Keep us informed if you come across any caterpillars - the WLH is still a target species for me.

Mike

Me too. I haven't seen them yet.

Denise

[eccles]

And me!

[Matsukaze]

Nothing doing yet, though the lime-green seed capsules on the elms are now out on most of the larger flowering specimens. Worryingly there is no sign of any feeding damage to the seed capsules yet, compared with spring 2007 when seeds on almost every tree had been 'nibbled'. That year I found a few caterpillars on various elms around Bathampton and Claverton Down, but have never seen the adult there, though I have looked and looked...

I also found the caterpillar a little way to the south of the park-and-ride at Odd Down, and it ought to be widespread to the south of Bath where the foodplant can be found quite commonly. There is stacks of elm in the first few miles of the A36 south from Bathampton heading towards Frome, which I have never checked for caterpillars for obvious reasons; the sides of the road are quite wooded and viewing of the adults would be difficult. One possibility is a substantial stand of elm just across the Limpley Stoke viaduct, inside the sharp bend to the left (ST780619).

Even more interesting is the old railway viaduct at Midford, now converted to a cycle path (ST760605). A few elms adjoin this, mixed among ashes at the southern end of the bridge. It is high enough that you can look into the tops of the trees and might offer chances of photographing the butterflies if they breed there. Across the bridge, the Hope & Anchor does fine food too.

[Matsukaze]

Did you all find the White-letter Hairstreak this year?

I saw a possible at the Limpley Stoke site (above); also two sparring over hedgerow elms at the A36/A366 junction (ST788568) a couple of miles to the south - though this would be a poor site for trying to photograph the butterfly.

[Denise]

I failed to see one last year
I'm hoping to rectify that this year, so if you know of a reliable spot, I would much appreciate it.

Thanks
Denise

[Roger Gibbons]

Of general interest regarding WLH, Liz Goodyear and Andrew Middleton (they who undertook the detailed study of Purple Emperors) of Herts & Middx BC have been undertaking country-wide research into WLH for the last three years and are soon to announce their preliminary findings. From what I understand, the results could be surprising to most of us in that WLH seems more widespread than thought, but it sedentary nature means that it is often missed.

Roger

[Lee Hurrell]

I saw my first WLH last year, in Greenford, Middlesex, (at an unknown sight I believe) which I will be adding to the sites page in due course.

And there is a recognised site at Horsenden Hill, Perivale, Middlesex already on there.

On a seperate note, am I right in thinking that Herts & Middlesex BC refers to the other Middlesex, where you will find Enfield (not Greenford)?

(Interesting county fact - apart from not actually existing geographically, Middlesex is the only county to have two seperate and completely non bordering areas, I think...)

Cheers

Lee

[Padfield]

Of general interest regarding WLH, Liz Goodyear and Andrew Middleton (they who undertook the detailed study of Purple Emperors) of Herts & Middx BC have been undertaking country-wide research into WLH for the last three years and are soon to announce their preliminary findings. From what I understand, the results could be surprising to most of us in that WLH seems more widespread than thought, but it sedentary nature means that it is often missed.

Roger

I'm sure you're right, Roger. I've found white-letter hairstreaks almost everywhere I've been, in England from East Coast to West, and on the continent, from central Oslo to Spain, but it is always something really special to see because of its exceptionally elusive behaviour. It flies in many - perhaps most - of the woods around Woodbridge, in Suffolk, where I used to live, and all the way up the coast, and around the coastal heathlands. At each site it seems to have a particular time of day when it comes down and is visible, but spends much of the rest of the day hanging around in the high canopy, often in ash trees. At one site along the Deben, in Woodbridge, I used to find it most easily at about 6.00pm, when it would come down to lower branches of large trees in woodland clearings. Near Oxford it came to bramble along paths in the early afternoon but was never there at other times of day. In Spain and Switzerland along the Rhône Valley I've found it nectaring at midday, but in what is now my local site, in my mountain village of Huémoz, it only seems to feed at 4.00pm to 5.00pm. The rest of the time you have to get your binoculars out and peer into the highest ashes, where you will often see it in good numbers. I'm sure the aspect of the sites and the directions of the woodland paths are very significant for the time of day at each site.

For those wishing to get a first glimpse in 2010, you need to know not just where, but when someone has seen one!

Here's a piccie from Huémoz to brighten the dark, winter evening:



Guy

[Paul]

Here you go.... two of the little WLH gems from a new site up here in N. Yorks...





If you look closely at the second one, allbeit fuzzy, I believe you can just about make out the fully formed catty inside

[Padfield]

Wonderful! They remind me of something I saw in Rendlesham in 1980...

I've been studying all the pictures on this thread to try and help me identify the wych elms. Then I'll see if I can get some piccies myself.

Guy

[Paul]

At this time of year Wych Elms are fairly thick set trees which sort of "spray out"... I'm sure there are better terms for it. The branches have a subtle zig-zag, and the important bit, the flower buds are more round and chunky than leaf buds... in my experience, only bother looking on last year's wood with flower buds present.
There... now you know (not!)

PS... never seen anything remotely UFO myself.

[Paul]

another egg find at a site locally where I've seen them before, but not for the last 2 years... things may be looking up!

[Matsukaze]

For anyone in the Bath/Bristol area still looking to see this butterfly, here are some sites:

Near Tunley (ST684593) - the butterfly must be breeding on a couple of tall elms in the hedgerow here. I checked it out one July morning around 9am and the hairstreaks were nectaring inconspicuously on creeping thistle and would have been easy to photograph had I remembered my camera; a friend saw them and photographed them on a couple of other occasions at about the same time of day. This particular field margin also has Marbled White, Large Skipper and the usual common grassland species.

Odd Down (ST724609) at the point where the road begins to descend from the plateau. Both sides of the road are fringed with flowering wych elms, and the butterfly will fly around these.

A36/A366 junction near Norton St Philip (ST787568) where the tallest elm on the western side of the junction is used as a master tree. The butterfly cannot be photographed here but it does appear to be a reliable site.

[Paul]

If anyone is looking, this is what the ~5mm catties look like this week in North Yorkshire.. not easy to find but.... if you don't look...



had to wire the twig down to the tripod in such a way the lens was the right distance... only way to keep it relatively still.... with a lot of care, nothing was damaged!

[Padfield]

That's a great picture, Paul!

For the record, all the elms I saw WLH caterpillars on last year are non-flowering. That's why I'd had such difficulty identifying the plants the previous winter - I was looking for flower buds and there weren't any. I checked very thoroughly this winter and none of the elms flowered.

The funny thing is, although I found a lot of caterpillars last summer, and there was a great summer brood of the adults, I couldn't find any eggs at all on the reachable branches this winter. That presumably means the eggs have been laid on high, non-flowering stems. It will be interesting to see if I find caterpillars low down again later in the year.

Guy

[Piers]

For the record, all the elms I saw WLH caterpillars on last year are non-flowering.

Regardless of what the accepted literature will have you believe, this is (as Tom Jones might say) not unusual.

Felix.

[David M]

Mat

Keep us informed if you come across any caterpillars - the WLH is still a target species for me.

Mike

There's a bona fide site near Cardiff where you will see them in July.