Friday, 3 July 2015

Cream-bordered green pea - is it actually resident in Carmarthenshire?

Looking into the life history (larval food-plants etc) of the cream-bordered green pea yesterday, I discovered an interesting online article, `Cream-bordered green pea Earias clorana (Linn.) - A Personal Account of its Occurrence in Cornwall ` by Phil Boggis, where the author tells of its discovery at Carlyon Bay in 1992 and ongoing, later sightings in subsequent years, with proof of breeding.
Interestingly, he notes that the variant found in Cornwall is ab. flavimargo (where the termen is yellowish) and he quotes Martin Honey in saying that `flavimargo is not found in native [ie SE/E English] populations`. This variant is believed to have been established by immigration, possibly from Brittany, the nearest area where it occurs.
I include below a photograph of the second brood individual that was caught at my garden trap at Tyrwaun, Pwll at the end of August last year, followed by a photo of the one caught at exactly the same site earlier this week. The yellowish termen is evident in the fresh-looking 2014 specimen, but this year`s individual is much more worn (perhaps not surprisingly for one at the end the flight period of the first brood), and it is seemingly missing the yellow colouration.
I had first assumed that the 30th June 2015 individual was a primary immigrant, as one had been seen in Cornwall (and had been posted, as was mine later, on `Atropos Flight Arrivals` - but no other sightings were reported). IF both the 2014 and 2015 Pwll individuals were  primary immigrants, then it is extraordinarily unlikely that I would have caught the only ones reported in Wales in both those years. Instead, I suspect that they are breeding locally, and I have mentioned before the profusion of many types of willow within the adjacent Llanelli Millennium Coastal Park plantings and elsewhere in SE Carmarthenshire. It is also relevant that I caught NO migrants at all during four consecutive nights` trapping - one would have expected some migrants at least to have accompanied this individual, if indeed it was part of an immigration. What was noteworthy though - and this was noted by more than one moth recorder - was that the balmy conditions triggered a more local movement and dispersal of moths, with species that normally did not occur in regular garden traps appearing. For example, Sam Bosanquet at Brechfa noted various wetland species, whereas I recorded various `conifer species`.
The literature (eg MBGBI) suggest that the cream-bordered green pea (as a caterpillar) prefers some of the thinner-leaved willows such as Salix viminalis or creeping willow Salix repens (which all occur at Pwll), but the established colony/s in Cornwall are reportedly using the widespread and common goat willow Salix caprea.
Does this moth breed elsewhere in South Wales? Sam Bosanquet had one at Stackpole, Pembrokeshire back in June 1991 though, incidentally, I don`t think that any undiscovered Pembrokeshire population was the source of this week`s Pwll individual, as there was a rather brisk, but warm, south-easterly on the night of 30th June.

                                                 Above: Tyrwaun, Pwll Aug 28th 2014.
                          Above: the quite worn individual, Tyrwaun, Pwll 30th June 2015.

7 comments:

  1. Should we infer that you believe it to be possible that the import of willow spp. whips for planting in the Coastal Park brought the founders of a new colony with it, or are there other willows even closer to hand where they may breed? Might it be possible to trace the origin of Coastal Park willows by speaking to site managers, or council officers?

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  2. No, I`m not implying that it colonised the area via planting stock, rather I`m suggesting that those willows, as well as other `basketry willows` planted in the 1800s, and also native willows in plenty, offer much potential habitat for it. What I am suggesting is that, like other moths (eg l-album wainscot), it is possibly in the early stages of natural colonisation. The that I article refer to, also states that other sites where it is established in Cornwall are already known, so that those that appear on `Atropos Flight Arrivals` may only be locally dispersing individuals, rather than fresh Continental colonists (though doubtless the latter occurs too).

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  3. Right, got it this time! Whatever the answer is, it's a very exciting time for you, Ian.

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  4. No probs Steve! Looks good for trapping tomorrow night (Sat), so I might do a couple of local sites....I`ve had some good sleep since the recent `mad moth marathon`!

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  5. I agree Ian, it seems too much of a coincidence. Now go out and find the larvae!

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  6. It certainly seems plausible that Cream-bordered Green Pea is colonising south Wales, perhaps from Brittany via Cornwall. It may now be present at a few, mostly un-trapped (coastal) sites - bearing in mind that the few active Pembs moth'ers are trapping in the west or north of the county and Ron is slightly inland - or may still be wandering across the water from England. I'd love to catch another one!

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  7. The trouble is that there`s far too much willow to search - even for a hundred of us!
    Wish I`d trapped last night (Fri), as the heavy thundery rain did n`t happen and tonight is n`t looking so perfect now...might do the garden traps though.

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