Drinking Nectar in the Sunshine

13 Jul

Before I moved to Scotland, I hadn’t appreciated how tall its national flower can grow. These thistles alongside our garden wall are as tall as I am – that’s 5’4” (or 163 cm to you metric types).

Today, they are aglow with small tortoiseshell butterflies. Small tortoisehells are more colourful than their large cousins, and I love the sapphire edgings to their wings. It’s a delight to watch them drowsily flitting from one flowerhead to another, unfurling their tongues and pausing for long minutes to drink nectar in the sunshine.

It is especially pleasing to see these small tortoiseshells, because I haven’t seen any for years and years. Their population in the UK has dropped by something like 80% over the last two decades, thanks (it is said) to the invasion of a parasitic fly from Europe, which lays its eggs in the caterpillars.

Perhaps it’s just my perception – I haven’t examined the figures – but it seems to me that Scotland is more protected than the rest of the UK against species losses caused by non-native species. I have not seen one single harlequin ladybird, a recent American incomer; yet it has apparently become so prevalent in England that our native two-spot and seven-spot ladybirds are under threat of extinction. The coniferous forests to the north of us have thriving populations of red squirrels that aren’t being ousted by the greys’ diseases. The biggest alien threat to Scotland’s indigenous species appears to be the rhododendron, and even this is receding.

Harlequin ladybird

I wonder how much of this species hardiness has to do with the northern climate and environment, how much has to do with human intervention, and how much with the fact that we are so far away from the Channel Tunnel.

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16 Responses to “Drinking Nectar in the Sunshine”

  1. Shailee July 13, 2011 at 1:35 pm #

    Interesting and informative :)

  2. seflopod July 13, 2011 at 4:32 pm #

    For the harlequin ladybird, it’s quite a recent invader from a particular direction and it would take it a little longer, at its currently obseved spreading rate, to reach Scotland. Meanwhile, the much colder Scottish climate is definitely going to favour those species which are already more adapted to that. Even in the south, the harlequin desperately squeezes itself into cracks in heated houses to hibernate through the winter. Whereas I’ve typically come across the native species making do with the nooks and crannies of trees and shrubs as sheltered places to curl up.

    • Snailquake July 13, 2011 at 4:35 pm #

      Here’s hoping the native ones can remain undisturbed up here in Scotland, then. I wonder about lacewings too – how will they fare now that the harlequins are encroaching on their niche?

  3. Jigme Datse Rasku July 13, 2011 at 7:13 pm #

    I’ll get back to you on that. The ladybird is very pretty as are the butterflies.

  4. SEF July 13, 2011 at 8:24 pm #

    Lacewings are still prevalent here despite the harlequins. I rather thought that all of them were encroaching on my niche – viz the inside of the house.

    • SEF July 13, 2011 at 8:25 pm #

      Hmm… that was meant to be a reply in the previous sub-thread.

      • Snailquake July 14, 2011 at 3:31 pm #

        I gather from some American friends that they frequently swarm inside houses over there to hibernate. Much to some people’s horror.

        • Snailquake July 15, 2011 at 3:20 pm #

          The ladybirds, I mean. Not the lacewings.

  5. dewimorgan July 13, 2011 at 10:08 pm #

    I’m… skeptical. So I did some further reading. While the 2-spot is apparently declining, neither it, nor the the 7-spot are at significant risk, from what I can see. Via Wikipedia:

    ===
    Harmonia axyridis (or the Harlequin ladybug) was introduced into North America from Asia in 1988 to control aphids but is now the most common species as it is out-competing many of the native species. It has since spread to much of western Europe, reaching the UK in 2004. [So, not America - Dewi.]
    ===
    The ladybird atlas “Ladybirds (Coccinellidae) of Britain and Ireland” published in 2011 showed a decline of more than 20% in native species due to environmental changes and competition from foreign invaders. The distribution maps, compiled over a twenty year period with help from thousands of volunteers, showed a decline in the numbers of the common 10-spot and 14-spot ladybirds and a number of other species including the 11-spot, 22-spot, Cream-spot, Water and Hieroglyphic ladybirds, Coccidula rufa, Rhyzobius litura and Nephus redtenbacheri [Guardian reports (http://www.guardian.co.uk/environment/2011/jun/15/british-ladybird-species-struggling) there being only ten species in decline, but doesn't ennumerate them, so the above may be an exhaustive list - Dewi]. Conversely, increases were seen in the numbers of Harlequin, Orange, Pine and 24-spot ladybirds as well as Rhyzobius chrysomeloides. The Kidney spot ladybird was recorded in Scotland for the fist time in recent years, probably due to climate change, and the once-extinct 13-spot was found to have recolonised Cornwall, Devon and the New forest. The most commonly recorded species was the 7-spot, closely followed by the Asian Harlequin — an invader that arrived from continental Europe [Not America - Dewi] in 2003 [note difference to above "2004" - Dewi] after being introduced to control pests. An ‘explosion’ in the number of Orange ladybirds, which feed on mildew, is thought to be due to the warmer damper conditions that now prevail in parts of England.
    ===

    So in summary: this is no “evil American squirrel invasion”. In fact, if there’s an invasion at all, America is also being invaded, too. Five “Native” species are on the rise, even from the brink of extinction. Ten species are declining. There is a plethora of species, 47 of them (maybe 48 including harlequin?), the balance of which is constantly shifting to deal with yearly and longterm changes in climate, as it has always been: some decline, others explode. The newspapers are just once again making a scary story about something we love, so everyone can get all het up about nothing. And now any time anyone sees a ladybird that has an unusual number of spots, they hate on it and call it a Harlequin.

    If you see a Harlequin, smile at it and say “Way to go, current rising star of the Coccinelida clan! Even though I’m not sure how to identify you or anything. For all I know you’re a Coccidula rufa, Rhyzobius litura and Nephus redtenbacheri. In which case, er, pretend I didn’t say anything.”

    http://www.harlequin-survey.org/recognition_and_distinction.htm may come in handy for such socially awkward meetings.

    • dewimorgan July 13, 2011 at 10:08 pm #

      Phear my procrastinatory prowess!

      • Snailquake July 14, 2011 at 3:28 pm #

        Thanks for the info. I shall have to look into it more, as I have plenty to procrastinate about right now!

        By the way, I don’t hate on grey squirrels. Just in case you think I do. More importantly, I don’t hate on the Americans – grey or otherwise!

        • dewimorgan July 14, 2011 at 8:40 pm #

          You hate the Harlequins! You dooooo! :P With their evil spotty backs and their beady eyes.

          But yeah – I’m skeptical of my research above, too, particularly the Wiki entries. The different years, for a start, plus I’m sure I saw harlequinny ladybirds earlier than 2000. And: “a decline of more than 20% in native species” – I suspect that might be supposed to read “a decline in more than 20% of native species”, which is what a lot of the news articles, including the Guardian one, were saying. that is, 10 of the ~50 species were in decline, rather than that the native population had declined by 20%.

          Astonishing the number of forms the harlequin comes in, too – I like the really round ones best.

          • Snailquake July 15, 2011 at 3:18 pm #

            I was going to check out the academic journals I have free access to thanks to being a student, but today’s procrastination took the form of getting sunburn in the garden.

            • DewiMorgan July 16, 2011 at 7:39 pm #

              Ooh! Now put little jam-jar-lid sized circles of black paper on your back, and you’ll be a ladybird yourself, kinda sorta!

              • Snailquake July 17, 2011 at 5:32 pm #

                Haha, by chance the sunburn pattern is not far off that!

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