Tuesday, 24 May 2016

Cryptic Wood White survey in Craigavon

It has recently been discovered that Ireland has two species of Wood White butterfly: Leptidea sinapis, which is restricted to the Burren and nearby areas (and is the same species as that found in Great Britain) and the Cryptic Wood White - Leptidea juvernica - which is found in the rest of Ireland, including Northern Ireland, but is absent from GB.

Resolution of the conflicting and confusing identifications and distributions was temporarily further confused by the suggestion that one of the species was Leptidea reali, which is found in France. It seems that the situation has now been satisfactorily resolved, and it now remains to examine local populations to be sure we have the correct distributions. There is no sure way of separating the species by morphological characters, although differences have been proposed, so the only way to be sure is to sample populations and examine the genitalia.

The purpose of yesterday's visit to Craigavon was to train recorders in the identification of Cryptic Wood White (CWW) and to demonstrate a recording system for subsequent use in tracking this (and other) species.

But me being me, I didn't restrict myself to CWW, and I recorded more or less everything else we encountered.

First, though, a shot of the courtship behaviour of CWW:

Courtship behaviour in Cryptic Wood White, Leptidea juvernica
The male (left) usually sits higher and repeatedly swipes his antennae and proboscis over the face of the female. This courtship can take up to 30 minutes to complete. If the female accepts him, mating takes place. We saw one recently-emerged female being courted by two successive males before her wings had even fully inflated.

Gorse bushes were very fruitful, and were covered with Gorse Shieldbug:
Gorse Shieldbug
And their eggs: 

Eggs of Gorse Shieldbug

I also found many specimens of the minute (3 mm.) Gorse Weevil, Exapion ulicis:

Gorse Weevil, Exapion ulicis

New to my Species List.

There were a great many Common Blue damselflies: 
Common Blue damselfly (Enallagma cyathigerum)
And a few Blue-tailed damsels:

Blue-tailed Damsel

I found a few galls of the mite Eriophyes pyri quite early on in the walk:

The gall mite Eriophyes pyri on Rowan.

This appears to be the first record for NI, with one previous record from Ireland, and new to my Species List.

A record shot of the Mirid bug Harpocera thoracica. The male antennae have an interesting 'structure'.
Mirid bug Harpocera thoracica (male)
New to my Species List.

The day-flying Mother Shipton moth caught my eye, and it posed conveniently for a few shots:

Mother Shipton moth
I have seen the Lacehopper Tachycixius pilosus quite a few times, but this one seems to have a mite of some kind under the left wing. Mites usually position themselves in places where they can't be scratched off.
The Lacebug, Tachycixius pilosus

Finally, a Tetragnatha sp. 'Stretch Spider'. There are a couple of these that can't be separated without a microscope:

Tetragnatha sp. 'Stretch Spider'
Not bad for around 2 hours work, and we did count around 25 CWW. 

3 comments:

Gill said...

Absolutely fascinating, and some great close-up shots.

I'm very intrigued by that butterfly distribution - how on earth does the "British" species get to the Burren but nowhere else in Ireland? Is it a habitat thing? I've never seen it and think it must be a rare butterfly this side of the Irish Sea?

stuart dunlop said...

The distribution is certainly strange, and didn't help the identification process. The first alert was that Wood White in general was increasing in Ireland, but decreasing in GB. Sampling showed that there were two species and their distributions actually meet in some locations. There are three species that occur in France, and at first the non-Burren one was identified as Leptidea reali, and became known as Real's Wood White for a few years, but is now known to be Leptidea juvernica and is called Cryptic Wood White. The Burren and GB one is Leptidea sinapis and is, unfortunately, known as Wood White. So we can't (in Ireland) point at a Leptidea specimen and say "that's a Wood White" because it probably isn't, unless you're in the Burren, in which case you'd be right. Habitat and food requirements appear to be identical, with the adults flying in low grassy areas, and the larvae feeding on Birds-foot Trefoil, Meadow Vetchling and Greater Birds-foot Trefoil, although there is some evidence that there is a differing preference for Greater between the species. (I just checked back in my blog and found that in 2004 and 2005 I referred to my local Wood Whites as Real's. How things change.....)

Gill said...

Ah, yes, I remember that - no wonder I'm confused! :-)