Friday, 1 July 2016

Success at last 30th June 2016

On several days over the last two weeks I have been going to a favoured local area in search of Black Hairstreak butterflies that I know occur there but have met with no success. The weather did not help, with an acute lack of anything remotely like sunny days but still I ventured out on the off chance that the occasional forecasted sunny spell might reap a dividend but consistently met with abject failure.

Undeterred I tried again this Thursday, as although rain showers were forecast and there was a large amount of cloud there appeared to be a chance of some sunshine in between the cloud and showers. As it turned out the showers did not materialise so I left home once again to try my luck.

Black Hairstreaks are the rarest of the five hairstreak butterfly species found in England and one of the rarest butterflies in Britain.They were first discovered in Britain in 1828 when an entomological dealer going by the name of Mr Seaman collected specimens from one of the most famous sites for this species - Monk's Wood in Cambridgeshire. These were at first thought to be specimens of the very similar White letter Hairstreak until Edward Newman, a Victorian entomologist, noticed they were different and declared them to be Black Hairstreaks

They have a very short flight period from about the middle of June to mid July and are not prone to wandering far from their birthplace. An entire colony will often confine itself to a single small area in a wood despite suitable areas being available nearby. This inability to colonise other suitable areas has doubtless had some effect in making it so scarce. They have a very restricted distribution in Britain confined to the Midlands, that follows a line of heavy clays stretching between Oxfordshire, one of its strongholds, in the south west and Cambridgeshire, another stronghold in the north east, thus making it a very desirable butterfly to enthusiasts of all things lepidopteran. Formerly there were up to ninety sites where they could be found but this has now declined to only about fifty sites. Couple this with the fact that this butterfly spends by far the majority of its brief time high in trees feeding on the honeydew of aphids, then you can see it requires no little effort and persistence to get to see them.

They like the edges of sunny woodland or narrow rides that are sheltered from the wind and where stands of mature blackthorn grow, their larval food plant and on which they will lay their eggs. The eggs are laid singly on young blackthorn in June and July and then overwinter before the caterpillar hatches towards the end of April and the green larvae feed on the flower buds and young leaves of the blackthorn. Pupation commences in June and the pupa looks like a bird dropping in an attempt to camouflage itself from predators.The adult butterfly emerges in mid to late June.

Black Hairstreaks are late risers and I rarely go looking for them before eleven in the morning by which time, if the weather is appropriate air temperature has warmed sufficiently and I can be confident that there will be a chance of some sunny spells to tempt them into activity. Midday is said to be the peak time for them being active.

Today was just such a day and on arriving at my chosen spot I found that no one else had thought it worthwhile. Butterfly watching and photographing has become a popular pastime these days and Black Hairstreaks, being so rare and hard to see are guaranteed to always attract enthusiasts. Once word inevitably gets out of their presence this area can get quite busy with butterfly enthusiasts from far and wide coming to try their luck, sadly not all respecting the environment and when a hairstreak is found the vegetation can become badly trampled by photographers which is totally irresponsible and un-necessary in my opinion.

I walked a few metres along a path by some blackthorn and came to an area of rank vegetation with a cluster of Hogweed stems holding high their flat white flowerheads on hairy green stems.

Hogweed and Blackthorn
Black Hairstreaks, despite their predilection for feeding in trees will occasionally come down to feed on the nectar from such flowers, Creeping Thistles being another favourite here. The best chance to see one well is to just stand and carefully examine each of these flower heads looking for a small triangular shape of closed brown wings on the top, for all the world appearing like a tiny sailboat amongst a froth of white foam. I duly examined each Hogweed flower head and joy of joys there was the familiar little brown triangle of a Black Hairstreak, progressing with mincing steps across the clustered florets of a Hogweed flower. 

Today it had taken no more than a few minutes to find a Black Hairstreak after hours of fruitless searching and the sense of triumph I felt was palpable. They are late in appearing this year but no less welcome for all that and this individual was pristine and surely had just emerged from its pupa. 

As is often the case when they are nectaring it was oblivious to any outside attention and despite my close proximity carried on wandering the flower head probing with its extended probiscis and feeling its way with its black and white banded antennae as it systematically covered each tiny floret in its search for the ambrosia of life.

After taking its picture I just stood and admired its delicate beauty. The underwings a medium brown with a bright orange band along the rear edge of the lower wings and a less distinct band on the upperwing. A row of ascendantly diminishing black spots enhanced the inner edge of the lower wing's orange band, extending onto the upper wing also. A tiny black spike or tail protruded from each of the lower wings and further in, on both the upper and lower wings were the thin white wavering lines from whence the name hairstreak comes.

Black Hairstreaks rarely open their wings when settled but for a brief moment this individual, irritated by the close proximity of a hoverfly slightly opened its wings and I could see orange on the edges of the upper surfaces of both the forewing and lower wing which identified this hairstreak as a female. I stood for over an hour as this small butterfly fed on this one flowerhead just inches from me, and during this time the clouds darkened and one of the forecast showers arrived. I assumed this would herald the departure of the Black Hairstreak for shelter but not a bit of it as it continued to feed undeterred, fully exposed to the rain during what became a reasonably heavy shower that lasted a good fifteen minutes.The rain abated and the hairstreak continued to feed, forever delicately probing. I left it still feeding and made my way further down the path, the only other butterfly species I saw were Meadow Browns. A couple of Banded Demoiselle flew from my progress, their dark wings and iridescent metallic blue bodies looking exotic, mysterious and exciting amongst the mundane greens of the hedgerow.

Banded Demoiselle
Meadow Brown

No comments:

Post a Comment