Thursday, 20 August 2015

The bluest of blue ...

Adonis Blue (Polyommatus bellargus)




P. bellargus is a species of chalk downland, where its discrete colonies may be found in warm, sheltered locations.

The male - three separate individuals pictured above - has the most intensely coloured blue wings that gives this butterfly its name. It can be found flying low over vegetation, seeking out the less-conspicuous females that are a rich chocolate brown in colour. Like its close relative, the Chalk Hill Blue (Polyommatus coridon), the distribution of this species follows the distribution of Horseshoe Vetch (Hippocrepis comosa), which, in turn, follows the distribution of chalk and limestone grassland. However, this species has a more restricted distribution than P. coridon, indicating more precise habitat requirements. This butterfly can be found in large numbers where it does occur, such as the chalk downloads of East and West Sussex. Mill Hill, Malling Down, Cissbury Ring and High and Over are all reliable sites and each holds variable populations.

This is a warmth-loving species, preferring sheltered, south-facing slopes where the turf is closely-cropped, probably because it provides a higher temperature for the immature stages or because this is a requirement for the ant species that attend the Adonis Blue larva and pupa. The loss of grazing by rabbits, for example, can cause the sward to become overgrown and can render a site unsuitable for this beautiful species.

Quite simply a stunningly beautiful creature …

Sunday, 16 August 2015

Thecla ...

Brown Hairstreak (Thecla betulae)

The beauty of betulae ...



T. betulae is the largest Hairstreak to be found in the British Isles. It is a local species that exists in self-contained colonies that breed in the same area season after season. Despite this, it can prove extremely elusive, since it spends much of its time resting and basking high up in tall trees and shrubs.

Adults emerge in the morning with males generally appearing a few days before females. This is a warmth-loving butterfly and is rarely seen on overcast days. On sunny days the adults will rest with wings open, absorbing the sun's rays on their dark brown wings, which gradually close as they warm up. In flight, the adults are easily mistaken for the Gatekeeper (Pyronia tithonus), which flies at the same time. The day flying male Vapourer moth (Orgyia antiqua), though somewhat smaller than T. betulae, is also often mistaken for betulae by some observers.

The males are the more elusive of the two sexes, congregating high on ash ‘master trees’ that are positioned around the breeding area, where they feed on aphid honeydew. They occasionally come down to feed on various nectar sources, probably when honeydew is scarce. When they do come down they can be remarkably tame and easy to observe. This is one of the latest species to emerge in the British Isles, with adults first seen on the wing in late July or early August. There is one generation each year. Two separate females are illustrated above.

Monday, 10 August 2015

Chalk Hill Blue

Chalk Hill Blue (Polyommatus coridon)





As its vernacular name implies, P. coridon is found on chalk downland, although limestone downland is also used. The adult butterfly is most-often seen in bright sunshine, where the ground may appear to shimmer with the activity of hundreds, if not thousands, of males actively searching for a female just a short distance above the ground. The distribution of this species follows the distribution of its larval foodplant, Horseshoe Vetch (Hippocrepis comosa), which, in turn, follows the distribution of chalk and limestone grassland. This species is therefore restricted to England, south east of a line running from Gloucestershire in the west and Cambridgeshire in the east. It is absent from most of central England, northern England, Scotland, Wales, Ireland, the Isle of Man and the Channel Islands.

It is univoltine with the adults emerging in mid July in typical years, a peak being reached at the end of July and early August. The 2012 emergence in Sussex was exceptional with numbers not recorded since the mid 20th Century. A detailed evaluation, undertaken on 3rd August 2012, estimated a population of 820,000 individuals at one site alone. This mass emergence is believed to have occurred due to the wet conditions continuously suffered throughout the spring and summer of 2012, which, in turn, would have led to an exceptionally lush growth of nitrogen-rich larval foodplant. The sexes are strongly dimorphic. The males - a single individual illustrated above - being a beautiful pale sky blue and the females primarily chocolate brown. The adults use a variety of nectar sources, and the males will also visit, often in some numbers, moist earth or animal droppings to gather salts and minerals. This is a highly-variable species and many named aberrations exist. Catch them in the right light and the males are simply stunning …

Hulme, N. (2013). The 2012 Butterfly Year. The Sussex Butterfly Report. Sussex Butterfly Conservation. Issue 5, Spring 2013, pp. 12-15.

Time for bed ...

Common Blue (Polyommatus icarus)

Captured in the last rays of the evening sun a female Common Blue goes to roost …


Friday, 7 August 2015

Brown Argus

Brown Argus (Aricia agestis)




A. agestis is a widespread, warmth-loving species and, as such, is typically found in sheltered areas or on south-facing elevations. It can be found south of a line between Dorset in the west and southeast Yorkshire in the east, along with colonies in Derbyshire, North Devon and Cornwall. It is also found in north and south Wales, but is absent from central Wales. It is not found in Scotland, Ireland or the Isle of Man. Occurring in small, compact colonies, it is not a great wanderer, only travelling a couple of hundred metres, at most, from where it originally emerged. Like its close relative, the Common Blue (Polyommatus icarus), this species will roost communally on grass stems at night. In fact, the two species are sometimes found roosting together.

Two broods are common in central and southern England, with only a partial second brood in north Wales and the north of England. In good seasons, a partial third generation may be recorded in the south. The adults emerge first in central and southern England in early May, peaking at the end of May and the beginning of June, and giving rise to a second brood that emerges at the end of July. In north Wales and northern England, the first emergence starts in early June with any second brood appearing in early August.

Unlike most other members of the Polyommatinae, the ‘blues’, the Brown Argus has no blue scales on its upperside, both sexes being primarily brown in colour as its vernacular name suggests - although the butterfly can exhibit a bluish sheen when at certain angles to the light. Both sexes have beautiful orange spots on the upperside of both forewings and hindwings with the female - illustrated above - being more generously marked. It appears to be doing well in Sussex this season …

Thursday, 6 August 2015

The harder you look the more you see ...

A favourite place …



I think we all have favourite places and one of mine is a rather magical location where the aromatic fragrance of wild marjoram stimulates the summer senses. Early season heralds the awakening of exotic orchids and delicate scented cowslips. Harebells gently chime in the wind like tiny elven bonnets. It is a place that always gives and only asks for respect in return to ensure its rich harvest continues into the following season. It is a place that is never silent, even on the quietest of days, as it resonates to the gentle harmony of countless hoverflies, grasshoppers and bees - even the flowers sing, as their dry, ripe and swollen seedpods rattle under every footstep. It is a place where beauty glides upon the breeze and sapphires dance. It is a place that is alive with living gems …