One of Westbury’s commonest dragonflies. Males, which are mainly blue, often swarm in large numbers.
2019 was a particularly good year for them.
Any Westbury Society News
One of Westbury’s commonest dragonflies. Males, which are mainly blue, often swarm in large numbers.
2019 was a particularly good year for them.
The Hawkmoths, Sphingidae are a widespread family of moths with more than a thousand species worldwide. They are usually large, broad-bodied strong flying moths whose caterpillars have a characteristic tail spike. Some members of the group have long tongues and feed extensively being able to use long tubular flowers as nectar sources, while others have reduced mouthparts and so do not feed as adults. In Britain there are 9 species that are resident and a further 8 others that are more or less regular immigrants, but which do not successfully over winter. In the Parish in the last few years 8 species have been seen that I have heard about, though only the Hummingbird and Elephant Hawkmoths are seen every year. Additionally, the Small Elephant Hawkmoth has been seen but not for a long time. The Hummingbird Hawkmoth was covered in this series on 5th August.
Elephant Hawkmoth: This characteristically ‘pink with olive markings’ moth has a long tongue and can feed easily from flowers like honeysuckle. It can be seen on the wing from May until early August. The usual caterpillar food plants are various willow-herbs and in gardens Fuchsias.
The large caterpillar, which is seen quite often, has two pairs of large eyespots on the segments just behind the small head, which, on being disturbed, it waves about, perhaps startling a would-be predator. The caterpillar forms a pupa in the leaf litter or in the soil below the food plant where it then over winters.
Privet Hawkmoth: This is the largest of our resident hawkmoths with dark chocolate coloured forewings. It flies in June and July but does not feed. The caterpillar food plants are wild and garden privet, ash, and lilac. The caterpillar itself, is bright green with conspicuous purple edged white chevrons. It can be found from July through to September and overwinters as a pupa sometimes over two winters.
Poplar Hawkmoth: This moth flies between May and July and can have a small second generation in August or September. Its wings are a patchwork of brown and grey and at rest holds its wings such that the hind wing projects beyond the front edge of the forewing. The eyed hawkmoth. The food plants of the caterpillars is a variety of poplars and willows. The caterpillar is green with white diagonal striping also similar to the Eyed Hawkmoth. Pupae are formed buried in the soil at the bottom of the food plant, and which then overwinters.
Eyed Hawkmoth: This moth flies from mid-May into July. Its resting position resembles the poplar hawkmoth but if gently disturbed it reveals big ‘eyes’ on its hind wings and rocks too and fro. This seems to ward off insectivorous birds. The caterpillar food plant is predominantly apple but also crab apple and willows. The caterpillar is green with pale diagonal stripes resembling the poplar hawk moth and can be found from July through to September or October. It pupates underground near the food plant where it overwinters.
Convolvulus Hawkmoth: This is the biggest of the hawkmoths mentioned so far. It is an immigrant with very variable numbers arriving mainly in late August through into November. It has an exceptionally long tongue and can feed easily on long tubular flowers, white, nocturnally scented ones seem particularly attractive. The fore wings are mottled in ash greys and there are pink markings along the abdomen resembling those in the Privet Hawkmoth. The larval food plants are various bindweeds and larvae are regularly found along the south coasts of the UK. However, they do not survive to over winter.
Death’s Head Hawkmoth: This is the rarest of Westbury’s Hawkmoths being seen only very occasionally. In 2019 11 caterpillars or pupae were found in Westbury and several were kept and emerged in captivity for people to enjoy seeing before release. This year, at least so far, none have been seen, but they have been seen in Westbury before, as they are shown in a photo of the Village postmaster in what is believed to be 1984.
As the largest British Hawkmoth, it is quite unmistakeable with dark patterned forewings and yellow underwings with black borders. The thorax has a very realistic looking skull like marking. Small numbers arrive in the UK from strongholds in North Africa and southern Europe every year. They lay eggs usually on potatoes but also on woody nightshade and the huge yellow caterpillars that grow rapidly can be found in August when lifting potatoes, or the large pupae may be found later buried in the soil amongst the potato plants.
The 11 from Westbury and, for that matter, the 5 from Easton might represent eggs laid by a single fertile wandering female who has flown in from North Africa. She spreads here eggs out between potato patches. The adults emerge a month of so later in September and are occasionally seen. They can enter bee-hives without being attacked, where their short tongues are able to feed on honey stores. If the adult moth is disturbed it squeaks which may be part of its defences against attack by bees when it is in a hive. The squeak might resemble sounds made by queen bees. Neither the adults nor the pupae can over-winter in the UK and it is probably entirely wishful thinking to hope that the spectacular, newly emerged moths might fly southwards to return to southern Europe and North Africa.
Clouded Yellow: This is a ‘white’ and so is closely related to the Large and Small Whites, Orange Tip and Brimstone. It is another migrant that, while it breeds over the summer in the UK, fails to over-winter except in very small numbers along the UK’s sheltered south coasts – the Isle of Wight and Dorset. As with the Painted Lady its permanent population is in North Africa and Southern Europe. Each year very variable numbers head northwards spreading out across Europe and Asia. They usually arrive in the UK in late May. The food plants of the caterpillars are members of the Pea family, particularly Clovers and Lucerne. In good years they can produce three generations but more usually two with adults appearing in August and then again in October. There is evidence of a return migration but not in the ‘clouds’ in which they can arrive in good years. The last ‘Clouded Yellow year’ was 2013 but they only appear in Westbury Gardens very occasionally and in most years not at all. The most likely place to see them in the Parish is on the top of the Mendips nectaring on knapweeds and scabious before flying onwards. It could be that there is limited growth of the fodder crops, Clover and Lucerne, locally, and so there is little opportunity for numbers to build up nearby, even in years of abundant immigration.
The butterfly is Small White sized but of more sturdy build and is a very strong flier being able to cross long distances over the sea. The typical form is a very distinctive golden yellow but about 10% of the females are a much paler yellow – called ‘helice’. These can easily be confused at a distance with brimstones and the other whites but the heavy dark markings around the edges of the wings are diagnostic. However, when the butterfly settles it almost always settles with wings closed so it is rare to see these distinctive upper surfaces except in flight.
Photos John Ball
Wall: This is another ‘brown’ and, like its relatives, its caterpillars are grass feeders. However, it needs sparse, open, grassy areas with bare patches where sunshine enables the butterfly to bask and warm quickly. It is a strong flier in these exposed habitats. The male has a thickened dark area on its forewings which are the sex brands. In inland areas of UK, in times past, it used to be common but has now become rare, only remaining relatively common at coastal sites around England, Wales, southern Scotland and Ireland. It occurs in small numbers on Westbury Beacon and along the Mendips but in much larger numbers on Brean Down. It does occur in Westbury gardens, perhaps one or two a year, and this year it has been seen on Broadhay during our particularly sunny and warm May. Typically, it has two generations a year with the first emerging in late April or early May. The eggs laid by this generation will go through their life history to emerge in July or August. The offspring of this second generation need to get to the third instar caterpillar stage at which it is then able to hibernate. The following spring the caterpillars will feed again and then moult to the 4th instar after which they pupate hidden deep amongst the grass tussocks to emerge in late-April or early-May. While habitat loss inland of suitably sunny, sparsely grassy, rocky sites has occurred, it is not believed to be the main reason for its dramatic decline.
The suggestion is that, with a warming climate, the first generation is emerging earlier in April and the corresponding second generation in late June and early July such that it continues to produce a third generation in late September. However, eggs laid by this third generation produce caterpillars that do not have sufficient time, before it gets cold, to reach the third instar, which is necessary for it to be able to over-winter. This means that there is a significant loss to the population every time there is an attempt at a third generation. The cooler habitats around UK coasts mean that there is less opportunity for the butterfly to produce this abortive third generation and thus they remain relatively common there.
Photos Peter Bright
Those keen on wildlife will be interested to see this report on breeding birds along the Strawberry Line. It suggests that the concentration of breeding birds along the line is greater than in much of the farmland the route passes through – another reason to support the development of off-road paths.
Painted lady: This is, perhaps, our most well-known migratory butterfly which arrives every year in the Spring or Summer. The adult butterflies breed here, and their offspring are being increasingly recorded as flying south again in the autumn. Painted ladies are a very strong flying butterfly and have been shown to cross from sub-Saharan Africa to North Africa and to reach even the most northern parts of Europe. Similar migrations occur across other continents. Seemingly during the northern winter, Painted ladies breed in North Africa and the offspring of these head northwards spreading across southern Europe and may even arrive in the UK.
More usually this generation will breed across southern France and Spain and it is the offspring of this generation that continue northwards arriving in the UK in May. Here they breed, with caterpillars feeding on various kinds of thistles and may go from egg to adult in as little as 6 weeks. This next generation may then continue northwards to breed again. In the Autumn something about the shortening days and falling temperatures triggers the newly emerged adult butterflies to head south.
Huge numbers have been recorded heading south and are able to once more return to the north African breeding grounds from which their great or great great grandparents left in the previous January. This strategy is so successful that the numbers estimated to return are much greater than the numbers that left. The benefit of this migration is believed to be related to a very effective wasp parasitoid that each year more or less exterminates any remaining north African Painted lady caterpillars. Migration means that the butterfly can evade this parasite and the successfully returning butterflies can take advantage once again of the ideal breeding conditions in north Africa over the northern winter before the wasp parasitoid multiplies once more. The extent to which sub-Saharan originating butterflies are part of the European annual immigration is not yet clear. While the occasional overwintering butterfly has been found e.g. in Cornwall, it seems clear that, as it has no ‘hibernation’ stage and caterpillars die when the temperatures fall below 5oC, it does not survive to any useful extent in the UK. The numbers that arrive in the UK each year are hugely variable and are, presumably, related to the particular conditions in the breeding grounds along their migration routes. 2009 and 2019 were the last ‘Painted lady years’ in which large numbers arrived in the UK.
This year a few have been seen in the Parish, but it has been only the odd one here and there. The fashion for purchasing captive bred caterpillars means that more people can see these wonderful animals up close and personal, but complicates knowing whether any particular butterfly has come from North Africa or from a local butterfly farm. They are a spectacular butterfly, and all the more so, because of their entirely migratory life history.
Photos Peter Bright
The striking colours of these Tigers is a sign that they are unpalatable to birds and so most of them can fly during the afternoon as well as at night.
Cream-spot Tiger: This moth is usually found in coastal habitats of the South West – Cornwall, Devon and Somerset and along the coasts of Dorset, Hampshire, Kent and Essex. It has appeared in Westbury for each of the last two years and occurs in a variety of inland places in the same counties. Its flight season is from late May to early July. The caterpillars feed on a range of herbaceous weedy species like white dead nettle, hawkweeds and ragworts. There is one generation per year and it is nocturnal and comes to light. It has been getting scarcer since 1990.
Photo Trevor Beebee
Wood Tiger: This is a moorland and heathland moth which occurs on Westbury Beacon and at Stoke Camp. This moth, along with most of these tigers, is active in daylight as well as at night. There is one generation and it flies from late May to July overwintering as a half-grown caterpillar. This feeds on a variety of herbaceous plants like ribwort plantain, salad burnet, and groundsel. It is widely distributed but local across the western and northern parts of the UK. It is declining in abundance in some places.
Photo John Ball
Scarlet Tiger: This striking moth is mainly found in south western Britain and is spreading northwards and eastwards and is becoming more abundant. It is active in the afternoon as well as at night when the males can be seen patrolling for females.
The caterpillar food plants are particularly comfrey and hemp agrimony. As the caterpillars get larger they feed openly by day especially in sunshine, and they disperse onto a range of other plants like bramble and nettle.
There is one generation flying in ‘June and July’. In Westbury this year the first was seen on 17th May and the last on 28th June so it has been an early season for them as well as for a whole lot of other butterflies and moths.
Photos Tina Westcott Robert Maxwell Wood Ollie Halls
Jersey Tiger: This, like the Scarlet Tiger, is a striking moth but has a forewing with stripes rather than spots. The underwings are orange or, less commonly, yellow. This moth is common on the Devon and Dorset coast but is now spreading northwards rapidly. It started being seen regularly in Westbury 5 or 6 years ago. It is likely that there is, each year, an influx of moths from the continent. Some have established on the coastal parts of Sussex and Kent. They have now arrived in London and are spreading northwards.
There is one generation per year with the adults flying from mid-July to early September. The caterpillar is found in rough and disturbed ground where its food is a variety of herbaceous plants like nettle, plantains and ground ivy. When it is a small caterpillar it over winters at the base of its food plants continuing to feed in the following spring and summer.
Photos Oliver Halls Robert Maxwell Wood Peter Bright
Ruby tiger: This is the smallest of this sextet of moths and is a dusky deep pink colour. There are two generations a year with adults flying mid-April and May and the second generation from July to the beginning of September. It overwinters as a fully grown caterpillar. It is a moth of open habitats like woodland clearings, downland, set aside farmland and gardens. There are a variety of herbaceous food plants including plantains and ragworts as well as spindle and broom. Like the other tigers the adults can be active by day as well as at night. Since 1970 it has shown large increases in distribution and abundance and is found across the whole of the UK.
Photos Peter Bright
Garden Tiger: This moth used to be common and widespread and was well known for its caterpillars – woolly bears with the irritating hairs. It is still widespread, but it has declined greatly in numbers and to a lesser extent in distribution. The cause of these declines is suggested to be increasingly warm and wet winters related to climate change. However, it is still found across the whole of the UK. There is one generation that flies in July and August. There are a wide variety of food plants including nettles and docks as well as various garden plants. The caterpillar overwinters as a small larva. It has been seen in Westbury once in the last 5 or 6 years that I know of. The photo was taken this year at Westhay.
Photo Jan Ward
Hummingbird Hawkmoth: This day flying moth is quite unmistakeable. It has a smart grey brown body with white markings along the sides and orange hind wings. With a 5cm wingspan and its continually whirring wings it makes a characteristic ‘hum’. Part of its scientific name is Macroglossum which recognises that it has a very long tongue which enables it to collect nectar, while hovering, from long tubular flowers like honeysuckle and red valerian.
It is a regular immigrant but is now managing to overwinter, especially in the south west of England. It is a resident moth of Southern Europe and North Africa and is found across Asia as far as China and Japan. In southern Europe it has two or three generations each year and over-winters as an adult hidden in a crevice. It is a strong flier and variable numbers come into the UK from France and Spain every summer maybe as early as April but particularly in July and August and lay eggs particularly on lady’s and hedge bedstraws.
The caterpillar is a characteristic green with the hawkmoth spike at the tail end. These home-produced moths are seen in September and October and an increasing number seem to be over-wintering successfully. This is another animal we are seeing more of because of global warming. There is a row for recording this moth on the Westbury Garden butterflies recording sheet.
Photos Robert Maxwell Wood John Ball Peter Bright
Small Copper: This handsome, brightly copper-coloured, small butterfly lives up to its name. It is about the same size as a common blue. It is widely distributed and found in a great variety of habitats across the wider countryside, where its chief food plant – common sorrel grows. Woodland rides, hedgerows, arable set aside, parks, gardens, and churchyards where it is relatively dry and open, and which contain suitable nectar sources.
They are, usually, only a few adults on the wing at the same time in their favoured sites. They over-winter as caterpillars which go into hibernation by the middle of October. In the following March, these caterpillars complete their development and pupate in April, after which the first generation emerges in the latter part of May or early June. The males are territorial chasing away other males and checking out any passing females. Eggs laid by this first generation, go through to pupate in late June and July such that the second generation emerges at the end of July and into August. These are the butterflies on the wing now.
A third generation is then produced which emerges in the latter half of September. It is this third generation, which can appear in large numbers in favourable years, as in Westbury in 2018 after the long hot summer.
Photos Mick Fletcher John Ball Peter Bright
Chalkhill Blue: This elegant butterfly, somewhat larger than the common blue, is confined, as its name suggests, to unfertilised chalk and limestone short grasslands. Ideally, and perhaps nearly essentially, rabbit grazing to create this short sward height is important. Certainly, scrubbing up of such habitats, as rabbit numbers have reduced, is connected to reduction in Chalkhill blue numbers. There may also be climate effects as many populations are struggling, at the moment, across England. The male is a stunning and unmistakeable milky blue colour while the females are milk chocolate brown. Both male and female have conspicuous dark lines through the white fringes on edges of the wings that the smaller common blues do not have. The butterfly is entirely dependent on horseshoe vetch which is, in turn, dependent on suitable grazing to keep the sward relatively short.
Horseshoe vetch flowers obviously in late May but otherwise the fine leaves of the plant are very inconspicuous. The caterpillars are also dependent on attendant ants that they supply with attractive secretions, who, in turn, benefit significantly from these as a food source. When the butterflies emerge in mid-July and perhaps flying into September the males are particularly conspicuous covering the colony area searching out unmated females. These females can be inconspicuous but are easily found nectaring on suitable plants such as marjoram and knapweeds and show off the dark lines through the white fringes of their wings. The eggs are laid on or near the foodplant but seem to fall easily to the ground, where they are invisible in the chalk or limestone rocky soil, and they spend the winter at this stage. The egg hatches in the following April and the young larvae begin their mutual relationship with the local ants such as the Yellow Meadow ant while feeding on the horseshoe vetch leaves and later flowers. It is possible that pheromones from ant trails help determine exactly where the female butterflies lay their eggs. The pupa is formed in June or July and is probably buried by its ant partners that are still collecting its secretions. Like other Lycaenids the pupa is believed to make ant-attractive sounds! The single generation is then ready to emerge in late July and onwards. In Somerset, Chalkhill blues are confined to the Mendips from Wookey Hole Fields to Brean Down and to the reserves on the Poldens. Most of the sites are in Nature Reserves of one sort or another where suitable grazing can be maintained. We are fortunate – if you want to see this spectacular, and Near Threatened, butterfly, that Westbury Beacon, Stoke Camp and Draycott Sleights are all good sites even if numbers have fallen in recent years. They could also be expected on Deerleap and Cook’s field if the food plant survives there as well. Please let me know if you see any, particularly in out of the way places!
Photos Peter Bright