BUTTERFLY: White-letter- and Purple Hairstreaks at Brockholes Wetlands, Lancashire

August 22 (and July 11), 2010:
The first decent weekend's weather for more than a month meant that many butterflies and dragonflies were on the wing on the Reserve. Six weeks ago, I was fortunate to obtain photos (above and below) of White-letter Hairstreaks (Satyrium w-album) there. Since then I had been hoping to get the chance to do the same with Purple Hairstreaks (Neozephyrus quercus). Boilton Wood at the Reserve's northern edge has both of these rather similar-looking butterflies and without doubt merits its SSSI status as a wild-life haven. White-letter Hairstreaks are closely associated with Elm trees (Ulmus spp.), especially Wych-elm, as this is their larval foodplant. Like many Hairstreaks they spend much time high in the tree canopy but will come down for nectar under favourable conditions. On this very warm sunny afternoon in July (the 11th), the weather was ideal, the bramble thickets below the trees were in full flower, and it was there that at least three of them were feeding on the brambles.




Being small, they were most easily located when in flight and needed to be watched carefully to find exactly where they had settled. Unfortunately, the subsequent poor weather appears to have curtailed their reappearance and it may be that this particular colony is only a small, somewhat isolated one. No doubt though, there will be several others elsewhere in these extensive woodlands.

Purple Hairstreaks (photos below) have a later and probably longer flight period. These are found amongst and close to oak trees (Quercus spp.) as this is their larval foodplant and, similar to the White-letter, they fly high in the leafy canopy and are also difficult to locate.




Today (August 22) they could be seen on two separate oak trees in warm but breezy conditions. It is interesting that they occurred in an almost identical situation to that of the White-letters although at a different place along the woodland's edge; they have in fact been seen in at least three separate places here recently.



When looking for both species this summer, even though conditions appeared ideal and the butterflies were known to be present, there were long periods of inactivity with none visible. Patience is needed to locate them.


[Typical habitat of both Hairstreaks, Brockholes]

BUTTERFLY: Holly Blues at Silverdale, Lancashire

August 16, 2010:
In brief sunny spells today a small number of Holly Blues (Celastrina argiolus) were flying. This is a site where I have seen them in the past and sometimes also earlier in the season when their larval food-plant is holly. By the month of August any of those flying are of the second generation and, perhaps strangely, the preferred food-plant now becomes ivy. Such behaviour is unknown in other British butterflies.



Here, males and females were associated with a short 50-metre stretch of sheltered, ivy-covered wall but unless it was warm and sunny they only settled briefly. Sometimes they would disappear from the site for long periods but would eventually return when the sun came out.



[Male, both above]


[Female]

The female differs from the male in having a dark grey border to the upperside of the forewing; in the male this is restricted to just a very narrow band. In the second generation female (as here) these dark markings become more extensive and can extend inwards from the wing edge. In exceptional years there may even be a third generation.


[Warm ivy-covered wall near Silverdale]

BUTTERFLY: Chalk-hill Blues (Lysandra coridon) at Aston Rowant, Oxfordshire

[Chalk-hill Blue male]

August 11, 2010:
Other than the Silver-spotted Skippers mentioned earlier (see below) there were also many Chalk-hill Blues (Lysandra coridon) flying today. Again, they remained mostly hidden when the sun was obscured but once it returned they were soon in motion and nectaring, especially on the Wild Marjoram (Origanum vulgare) which was in full flower. The males were bright silvery-blue on the upper surface of the wings which contrasted noticeably with the duller brown wings of the females. This butterfly, although restricted to southern Englnd, is much more common than the Silver-spotted Skipper and was very numerous at the site.



[Chalk-hill Blue female, above]


[Chalk-hill Blue male, above]


[Aston Rowant: the short grazed grassland habitat of the butterflies]

The Brown Argus (Aricia agestis), another of the 'blues', was also very frequent here. Both sexes are a rich brown on the upper side of the wings with prominent orange spots towards the outer margin. They also were attracted to the strongly scented Marjoram.

[Brown Argus, below]




Common Blues, Meadow Browns, Small Coppers and Small Heaths were also frequent.

For Silver-spotted Skippers at Aston Rowant today, please see below.

BUTTERFLY: Silver-spotted Skippers (Hesperia comma) at Aston Rowant, Oxfordshire

August 11, 2010:
Following a lack of improvement to the dismal summer weather locally, the forecast for some decent conditions in southern England prompted a day-trip to the Chiltern area to see the Silver-spotted Skipper (Hesperia comma).

This is a relatively rare butterfly in Britain and is at its north-western European limit in southern England. Aston Rowant, close to where the M40 motorway cuts a deep groove through the chalk hill-side, is one of its strongholds and is the most northerly British colony of any size.





This is a late-emerging, single brooded butterfly not on the wing until late July but which then continues to fly throughout August. It is restricted to warm, south-facing slopes on chalk downland where the turf is kept short by grazing and its larval food-plant, Sheep’s Fescue, grows. At Aston Rowant, on the steep warm hillside, there were many small bare patches of chalk presumably exposed by rabbits and it was on these warm areas that the butterfly sometimes basked. However, once the sun went in they would cease to fly but would immediately resume on its return.



[Basking over warm patches of chalk exposed by rabbits]

The butterfies flew fast and low and being of a dull greenish-ochre colour below were hard to follow. However, once settled the prominent silver spots, especially noticeable on the underside of the hind wing, could be seen. The females were darker in colour than the males, the latter having a line of dark scent scales on the forewing similar to some other skippers such as the Large Skipper. A wide range of nectar plants were apparently used but thistles and composites were probably the most favoured. There must be a very large population here as they were regularly encountered over most areas of suitable downland.


[A heavily marked female, above]



Although the most frequent skipper was the Silver-spotted, a few Essex Skippers (Thymelicus lineola) were also seen. These are much more widespread in Britain and nothing like as scarce. The Essex can be distinguished from the very similar Small Skipper by having black tips to the underside of their antennae (rather than brown as in the Small). Also, they have a shorter line of dark scent scales running parallel to the outer edge of the fore-wing, not longer and angled away as in the Small.



[Essex Skippers, showing the black underside to the antennae and characteristic line of scent scales]

BUTTERFLY: Two subspecies of the Large Heath in Cumbria

July 5 & 8, 2010:
The Large Heath (Coenonympha tullia) is a member of the family of ‘brown’ butterflies which includes the Meadow Brown and Small Heath. It is quite scarce in the UK where it is has a high priority conservation status. In the south of its range it is only found at a few localities in Wales and northern England but is more frequent in Scotland. In Europe it is designated as ‘vulnerable’ and is in decline in many countries.


[subsp. davus, the southern and most strongly marked form with many well-defined eye-spots]

The Large Heath has a specialised habitat requirement: lowland raised bogs, blanket bogs, or damp acidic moorland. Its main larval food-plant is Hare’s-foot Cottongrass (Eriophorum vaginatum). As well as flying in sunshine it can also do so in dull weather provided that it is warm. When feeding on its usual nectar source of heathers, epecially the Cross-leaved Heath (Erica tetralix), it invariably settles with it wings folded so making the upper-sides difficult to examine.


[Typical raised bog habitat of the Large Heath with the yellow Bog Asphodel in the right foreground]

Seen at an acidic bog in north Cumbria in the cool dull conditions pertaining on July 5th, only a few were flying in the more sheltered depressions in the bog but others were well concealed in the heather. The butterfly here is subspecies polydama, so defined by the strength of its wing markings being intermediate between those of the more southern UK localities (subsp. davus) and those of northern Scotland (subsp. scotica).



[subsp. polydama, the less clearly marked, intermediate form from north Cumbria (both above)]

Three days later on July 8th at its classic site at Meathop in south Cumbria, many subsp. davus were flying in breezy but much brighter conditions. This locality and the one seen in the north earlier appear very similar in habitat and vegetation. However, differences in the markings on the butterfly’s underwing are very apparent with those at Meathop showing much more well-defined spots (ocelli) whereas those at the other site (subsp. polydama) have paler wing undersides and fewer, less clearly defined spots. In the far north of Scotland, the underside spots are scarcely visible (subsp. scotica). How clear-cut these subspecies are in reality may be debatable since there seems to be a gradual transition from south to north.



[subsp. davus at Meathop (both above)]

When seen in flight at a distance, it might perhaps be confused with the Small Heath (Coenonympha pamphilus) since the differences in wing-span are relatively slight.


[Small Heath]

BUTTERFLY: High Brown-, Dark Green- and Silver-washed Fritillaries in Cumbria

July 3-8, 2010
In south Cumbria, all three of the larger Fritillaries have now emerged. They are fast-flying, large orange butterflies which inhabit scrub and woodland clearings, especially over limestone, where their bright colouration makes them highly conspicuous. All of them rely on various species of violet for their larval food plant.

Three photos below: High Brown Fritillary:





Two photos below: Dark Green Fritillary:




Two photos below: Silver-washed Fritillary.




When seen in flight these three Fritillaries are difficult to distinguish from each other and even when viewed from above, if perched, they still appear very similar. However, a good view of the underside of the hind-wing makes matters simple. In this respect, the High Brown Fritillary has an additional row of brown, silver-centred, spots (ocelli) lying between the outer margin of the wing and the inner row of seven large silver spots. These ocelli are not present in either the Dark Green or the Silver-washed Fritillary. The High Brown Fritillary also has a brownish tinge to the underside of the hind-wing, whereas in the Dark Green Fritillary it is greenish; in the Silver-washed it is conspicuously silver-banded and almost unspotted.

The markings on the upper sides of the fore-wings also differ, but only slightly. In the High Brown Fritillary the third dark spot (from the wing tip) in the obvious line of spots set inward from the chevrons, is out of line with the previous two whereas in the Dark Green, all are in line. In the Silver-washed, whilst these spots are aligned, they tend to tail off into almost insignificance towards the wing tip. Additionally, the male Silver-washed Fritillary has four very prominent black veins of scent scales on the upper side of each fore-wing.

DISTINGUISHING CHARACTERS
[High Brown Fritillary (both below), showing the additional ocelli on the under-side and the out-of-line third spot on the upper]





[Dark Green Fritillary (both below), showing the absence of ocelli on the underside and the in-line third spot on the upper]





[Silver-washed Fritillary (both below) showing the prominent silver bands on the under-side and the row of diminishing spots and the male's dark scent veins on the upper]




The High Brown Fritillary is now very scarce in this country with south Cumbria being one of its main strongholds