Chasing clouds ...

Clouded Yellow (Colias croceus)

The Clouded Yellow (Colias croceus) is primarily an immigrant to the UK, originating from North Africa and southern Europe, with numbers varying greatly from year to year. Each season, we normally see at least a few reaching our shores and, occasionally, they arrive in large numbers; such as the estimated 36,000 that appeared during 1947 when good numbers of much rarer migrants, such as Bath White (Pontia daplidice) and Pale Clouded Yellow (Colias hyale), were also recorded.

In more recent years, it has been shown that this species has successfully overwintered in the south of England. However, it is believed that the majority of individuals perish, since both larva and pupa of this continuously-brooded species are easily killed by damp and frosty conditions. In good seasons, C. croceus can produce up to three generations in the UK. In flight, the orange-yellow colour is quite distinctive, and unlike any other species. The pale helice form, occurring only in the female, is a creamy white, rather than yellow in colour and may lead to confusion with other similar species.

This strong-flying species always settles with its wings closed and so the dark borders on the uppersides of the wings are only clearly visible when in flight or when viewed backlit at rest. There is no elaborate courtship and, having mated, the female is subsequently able to lay an extraordinary number of eggs; up to 600 have been recorded from a single female.

Two females from 2013 above ...

Precious metals ...

Surrey Downland, 30-31 July 2013

The Silver-spotted Skipper (Hesperia comma) is a warmth-loving species. Its range contracted during the 20th century due to a reduction in grazing stock as well as the onset of myxomatosis in the early 1950s, which severely affected rabbit populations; the butterfly requiring closely-grazed chalk downland sites on which its primary larval foodplant, Sheep's-fescue (Festuca ovina), grows. Recent years have been more promising and this is one of the few species that is increasing its range. It is still relatively-local, with current strongholds being located in the Chilterns, Hampshire, the North Downs between Guildford and Reigate, East Sussex and south-east Kent. It occurs locally in my own county of West Sussex and is currently showing a positive trend for expansion into adjacent suitable habitat.

It is easily identifiable, since it is the only golden skipper found in the British Isles that has the distinctive white spots on the underside of the hindwings, which give the butterfly its name. Like other ‘golden’ skippers, the male is distinguished from the female by the sex brand on its forewings, which is a line of specialised scent scales.

H. comma is one of the latest species to emerge, typically not appearing until late July or early August, and it is then on the wing until early September. There is one generation each year. Like most skippers, this is a fast-flying species that flies close to the ground, and can be extremely difficult to follow when in flight. Both sexes spend the majority of their time either basking or feeding, and a wide variety of nectar sources is used. The butterfly will find the warmest patches of ground on which to bask, enjoying the warmth of paths, rabbit scrapes and other patches of bare earth, which have been baked by the sun. The males rest on suitable sunlit perches, and will investigate any passing butterfly, in the hope of finding a mate. If a virgin female is encountered, the pair exhibits a tumbling courtship, with the male eventually forcing the female to the ground where mating takes place. An egg-laying female locates a suitable patch of bare ground, such as a rabbit scrape, and then walks to the edge of the patch looking for a suitable location on which to lay a single egg.

A female at rest pictured below ...

Coridon ...

Surrey Downland, 30-31 July 2013

Simply wonderful …

I recently spent two days, with good friend Nick Broomer, searching several areas of chalk grassland on the beautiful Surrey downland; our targets, the beautiful Silver-spotted Skipper and the enchanting Chalkhill Blue. We were not to be disappointed on either count.

Although Tuesday was accompanied by persistent rain for much of the day, an early morning arrival provided ideal conditions for searching the grassland for roosting butterflies; we were not disappointed and found many hundreds, probably thousands, of roosting Chalkhill Blues over much of the hill. This included a number of nice aberrant specimens including those pictured in the two images below, referable to ab. postcaeca, Bright & Leeds (1938). The first image shows a particularly well-marked male which we observed from shortly after emergence until its first flight. Wednesday started warm, and by midday large numbers of insects were on the wing. As the sun pushed through the clouds the numbers of Chalkhill Blues increased and we were privileged to witness a magnificent display as the air and ground around us turned blue as if covered in tiny sapphires. It is difficult to estimate actual numbers, though if I were pressed to do so, there were certainly many thousands and probably many tens of thousands on the wing; possibly many more. Although I didn’t witness the peak of the Sussex Chalkhill Blue explosion last year, Wednesday’s display was an event to remember ...

A privilege to have shared with a good friend …

Black magic ...

Bernwood Meadows, 27 June 2013

The Black Hairstreak (Satyrium pruni) is one of the rarest and most elusive butterflies in Britain. It is also one of the most recently discovered (1828), due to the similarity with its close cousin, the White-letter Hairstreak (Satyrium w-album).

S. pruni is not a great wanderer and an entire colony will often restrict itself to a single area within a wood, despite there being suitable habitat nearby. This inability to colonise new areas at a pace, in balance with habitat loss, may partially explain the scarcity of this species. This butterfly has a very restricted distribution that is confined to a line of clays between Oxfordshire in the south-west and Cambridgeshire in the north-east. Colonies are typically located in small woods or nearby hedgerows, where blackthorn, the main larval foodplant grows. Sites are located in sheltered but sunny positions and typically have a southerly aspect to them.

The adult stage has an extremely short flight period, being typically seen in the last two weeks of June and the first week of July. There is a single generation each year. Upon emergence, the adults spend much of their time resting high up on maple, ash or the larval food-plant, crawling over leaves and twigs, in search of aphid honeydew from which they feed. Primarily an arboreal species they will occasionally come down to feed on various nectar sources including man made attractants. As with all hairstreaks, when active, they are extremely difficult to follow. To make matters worse, the Black Hairstreak is often found in the company of both White-letter and Purple Hairstreaks and distinguishing these three species in flight is almost impossible.

A male feeding pictured below ...

Vespa crabro ...

West Sussex, 20 June 2013

Royal appointment ...

The European hornet, Vespa crabro, is the largest European eusocial wasp; the queens averaging around 3cm in length (the queen pictured below measured 3.5cm, with a wingspan of 5.5cm). With the exception of the Median Wasp, Dolichovespula media, whose queens resemble small worker cast hornets in size and colour (D. media is yellow and black with small areas of red whereas V. crabro is a brown, red and yellowish-orange species lacking any deep black markings), it is unlikely to be confused with any other species.

Once only common in central southern England, it has now extended its range from Cornwall to Kent and northwards into Yorkshire. It has also been recorded from The Isles of Scilly, Isle of Wight and the Channel Islands. It is found in many lowland habitats, but is particularly associated with ancient deciduous woodland.

Queens emerge from their over-wintering sites in early April and nests are initiated, usually in hollow trees or similar cavities, in May with the first workers generally appearing around late June to early July. New queens and males, which emerge from the nest from September to October, mate and then disperse, with the males dying and the newly-mated queens seeking over-wintering hibernation sites. Back at the nest, which may persist into November in mild seasons, the old queen and remaining workers eventually die-out. V. crabro predates on a number of invertebrate species including other social wasps, honey bees, flies, butterflies, moths (hornets can forage in moonlight) and spiders. Prey is often taken from flowers and the vegetation of trees. In late summer and autumn, workers are sometimes attracted to exudations from deciduous trees; particularly oak. Workers, males and new queens will also visit Ivy, Hedera helix, blossom for nectar.

Big game ...

Iping Common, 17 June 2013

There are five species of Tiger Beetle in Britain: Cicindela campestris, Cicindela hybrida, Cicindela maritima, Cicindela sylvatica and Cylindera germanica. Of these, the Heath Tiger Beetle (Cicindela sylvatica) and the Cliff Tiger Beetle (Cylindera germanica) are both UK Biodiversity Action Plan (UK BAP) species; meaning they are species of conservation concern and action is being taken to protect and conserve them and their habitats. Two species have been recorded in Sussex. These include Cicindela campestris and Cicindela sylvatica.

The commonest, and possibly the most attractive of the British species, is the beautiful Cicindela campestris, the Common or Green Tiger Beetle. C. campestris is a fast, long-legged, agile predator that is easily recognized due to its iridescent green and purple colouring, along with its distinctive yellowish spots on the elytra. The adults, which can be seen from April to September on dry heaths and other sandy places, fly and run actively in the sunshine.

Grizzlies ...

West Sussex, 10 June 2013

The tiny Grizzled Skipper (Pyrgus malvae) typically occurs in small colonies of less than 100 individuals. It is found in England south of a line extended from West Gloucestershire in the west to North Lincolnshire in the east, with strongholds in central and southern England. There are scattered colonies further north and in Wales. This species is absent from Scotland, Ireland, the Isle of Man and the Channel Islands. Despite the suggestion in its specific name, malvae, P. malvae larvae do not feed on flowers of the mallow genus; though several closely related European species do feed on Malvaceae.

The adult emerges in late April, the first of the British Skipper species, and usually flies until the end of June. There is one generation each year, although there may be a small second brood in some seasons, when conditions are favourable.

This is a warmth-loving species, and both sexes bask in the sun for long periods, typically on a stone, leaf or bare earth. This is an active insect which will fly at most times the day, and even into the evening, if conditions are warm enough. The male is somewhat territorial and will chase any butterfly, irrespective of size, from its area. Females entering the territory are courted for a short period and, if the female is receptive, pairing occurs. The butterfly can be found roosting on heads of flowers and grasses during cool weather and at night.