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

There are 4 hairstreaks that have been seen in the Parish of Westbury, but they are all rare and, maybe, particularly hard to notice as well.  Green hairstreaks are over, Purple and White-letter hairstreaks are flying now and Brown Hairstreaks fly from mid-August into September.

  Green Hairstreak:   The butterfly overwinters as a pupa, unlike the other hairstreaks that over-winter as eggs.  These handsome bright green adult butterflies emerge from mid-April through to the beginning of June.  It is the underneath of the wings that are green and, settling with wings always closed, you do not see the brown upper sides of the wings.   They do well in areas with scrubby vegetation mixed with shrubs.  The males are territorial flying out to investigate any passing butterfly for females.  The eggs can be laid on a wide variety of food plants such as bird’s foot trefoil and common rockrose, and on the shrubs buckthorn, dogwood and gorse.

 

 

 

By the end of July, the caterpillars are fully developed, and the pupa is formed hidden at the base of the vegetation.  Like other members of the Lycaenid – Blue Family, there is some relationship with ants, and it is perhaps as pupae that the ants offer some protection.  The pupa is reported to squeak just like an ant!

Photos  John Ball    Peter Bright

 

 

White-letter Hairstreak:  This is the rarest of this quartet and has suffered greatly from the loss of elms from Dutch Elm disease.  It is entirely dependent on elms and has a preference for Wych elm.  The adults, about the size of a common blue,  emerge in late June and can fly for the whole of July.  They feed on aphid honeydew and can spend their whole life at the tops of elms and so be almost invisible.  Some may come down to visit flowers at ground level in the early morning or late afternoon as do Purple Hairstreaks.

The adult butterflies rest with wings closed showing the white W that gives it its name.  It has tails and eyespots on the hind wings which is believed to protect it from fatal bird attack with some flying butterflies being seen with this part of the hind wing missing.  The eggs are laid on small twigs of any of the various elms and it is in this stage that it overwinters.  The newly emerged caterpillars feed high in the canopy during March, April and May, and pupate in late May or early June to emerge at the end of the month.  One was seen in Westbury in 2011 and another in 2019 and there are regular reports from Lord’s Wood near Pensford, but there is nowhere you can guarantee to see them.

Photo  Peter Bright

 

 

Purple Hairstreak:  This is a butterfly of oak woods or even single oak trees.  During June and early July, the pupae are formed in the vegetation at ground level below oak trees.  It may be that at this stage as well as a caterpillar, that there is some relationship with ants to which they can ‘sing’!

The adults emerge from pupae at ground level and having expanded their wings fly up into the oak tree canopy.

There, the silver undersides of the flying butterfly can be seen flashing in the sunlight high in the tree.  The upper surfaces of the wings have a purple sheen that shows as they bask in the sunshine.  They are a little larger than common blues.  The adult butterflies can spend their whole life high in the canopy feeding on aphid honeydew and mating out of sight of human observers.  They are reported to come down to ground level to nectar on flowers in the early evening so are hard to find at ‘normal butterfly times’ in the middle of the day.

The eggs are laid at the base of oak buds and it is at this stage they over-winter. The following March, April, and May the caterpillars feed inside the developing buds later transferring to eating the young developing leaves at night after resting camouflaged on the twigs.  Fully mature at the end of May the caterpillar descends to ground level once more.  This is the most abundant of the hairstreaks but being so hard to see its distribution and numbers are extremely hard to gauge accurately.

Photo    Mick Fletcher  John Ball   Peter Bright  Simon Bright

 

 

Brown Hairstreak:  This handsome butterfly is the largest of the hairstreaks being about the size of a gatekeeper.  It is a butterfly that depends on Blackthorn and needs 2 and 3-year-old young shrubby growth on which it lays its eggs in late August and September.  Flailing of blackthorn hedges every year is a disaster.

Management for Brown Hairstreaks means cutting blackthorn back on a 3-year cycle.  They overwinter as eggs and the easiest way to detect the presence of this elusive butterfly is to look for the bright white eggs laid in the forks of small twigs.  On hatching in early May, the caterpillar feeds inside the young leaf buds but transfers to eating the young leaves as they appear in May and June.  The pupa is formed in July in the ground and it seems that it may be buried by ant activity in a cell of dry earth.  The adults emerge in August and September.  The males gather in assembly trees such as tall hedgerow ashes feeding on the aphid honeydew and waiting for the visiting females.  After mating the females search out suitable blackthorn so that they are the ones that people come across easily at human eye-level.  The males rarely come down from the tall trees where they spend their time and so are hardly ever seen.

 

 

Several Brown Hairstreaks have been seen in the Village but on the lower parts facing onto the moor.  It is reasonable to speculate that there are colonies in the Parish somewhere on the hedgerow blackthorns that are not cut every year.  The Somerset strongholds are in the centre of the county around Taunton.

Photos  Peter Bright

  

Comma:  This is really a woodland butterfly that has had times in the past when it became quite rare.  However, since the 1960s it has increased dramatically in numbers and has spread northwards reaching Scotland in 2000.  It is now a familiar butterfly of woodland edges, hedgerows and gardens.  The butterfly is named for the white mark on the underside of the hind wing though on the other wing it will resemble a C which is part of its scientific name, Polygonia c-album.  The adult butterfly overwinters, presumably in sheltered places in its woodland habitat but not in our garages and outhouses.  On emerging from hibernation in late March or early April the males take up territories investigating any passing butterfly looking for females.  Pairing is believed to take place high in the woodland canopy after which the female prospects for suitably sunny but sheltered food plant.  In the past a much used foodplant was hop but now the main food plant is nettle but it has been found on a variety of plants such as currants, elms and willows.  The caterpillar feeds inconspicuously on the underside of the leaves of its food plant but by the time it reaches the last, 5th instar, its colouring has been transformed such that it now camouflaged looking like a white bird dropping.  The pupa is formed hanging amongst the vegetation of its food plant.  The adults of the next generation emerge in late May or early June.  These come in two forms – the normal darker form and a much paler form, hutchisonii.  The normal form feeds up on nectar and goes into hibernation in August.  The paler, hutchinsonii, mate and lay eggs that go through their caterpillar and pupal stages emerging in late August and September as a second generation.  These are the late season butterflies which will then, themselves, go into hibernation in late September or October.  There is, therefore, a mixture of one and two generations in its life cycle.

Photos   Robert Maxwell Wood    Peter Bright

Silver-washed Fritillary:   This magnificent, bright orange insect is close to the largest British butterfly and is certainly the largest in Somerset now.  This colouring is also why in some parts of the world this group of butterflies are called leopards. It is a butterfly of woodlands that have an abundance of violets growing around the moss-covered bases of trees, particularly oak.  Woods that are coppiced or thinned have an abundance of bramble, a favourite nectar source, as well as encouraging a good growth of violets. 

They spend a lot of time high in the canopy and feed on the abundance of honey dew on the leaf surfaces.  In some years these strong flying butterflies come into gardens using plants like Hebe and Buddleia as convenient nectar sources. The adults emerge in late June or July and may continue to fly into the middle of August.  They are fast and powerful fliers and the males patrol the woodland rides and canopy investigating any orange butterfly checking for virgin females.

If such a female is found there is a spectacular courtship flight with the male showering the female with pheromones from the sex brands on the front wings that show as dark lines along the middle two veins.  Following this the female seeks out patches of violets but having found them, then goes to a nearby mossy covered oak trunk base where she lays eggs, singly, in mossy crevices.  There is a fabulous colour variation of the females which is a deep bronze green colour called valesina.

It is possible that this dark colouration is favoured in poor summers as the butterfly warms up more quickly, but it is at a disadvantage in normal summers as the males take longer to find these unusually coloured females.  The newly emerged 1^st instar caterpillar eats its way out of the egg and immediately hides itself in a bark crevice where it passes the winter.  This could be why ash and beech woods are unsuitable lacking the appropriate moss filled bark crevices.  From early April the young caterpillar comes down to the woodland floor and feeds on the nearby violets.  When fully grown the caterpillar goes up a nearby plant to pupate a metre or two off the ground.  The next generation of adults emerge in late June providing another spectacle of summer in Mendip woodlands.

Photos    Peter Bright

 

 Dark green Fritillary:     This is typically a butterfly of windswept limestone grasslands but is also found on bracken covered hillsides, grassy dunes and a variety of similar habitats.  It is named for the green wash on the underside of the hind wings.  They need the sward to be of medium height so that heavy grazing, or complete lack of such, can make the violets that are its caterpillar food plant unsuitable.  It should be much more widespread across the Mendip scarp than it is but, it is doing well at Ubley Warren.   Single individuals have been seen on the Beacon and even in a Westbury garden over the last few years. 

With suitable grazing and clearing of gorse there is hope that the butterfly will return to the Beacon once again.  The adults emerge in June and will fly for much of July and perhaps into early August.  They fly strongly and can cope with their windy habitat and have a special fondness for purple flowers like knapweed as nectar sources.  The males will patrol large areas searching for virgin females investigating any suitably coloured butterflies.  After mating, the females will hide while their eggs mature and will then search out the violets growing in suitable places before laying near to them.  As with the Silver-washed Fritillary, the newly hatched caterpillar immediately finds a hiding place in which to hibernate.  Towards the end of March in the following year the caterpillar emerges from hibernation and seeks out violets on which to feed.  The later instar caterpillars are particularly black and spiky and may be seen travelling across open spaces seeking new supplies of violets. 

The blackness presumably enables the caterpillar to warm up quickly in its otherwise exposed and cool habitat. In a very tall grass sward it may, therefore, not be able to warm up quickly enough to survive.  In the middle of May or beginning of June the caterpillars will find hidden places to pupate and the adults will start emerging again from the middle of June.

Photos   John Ball    Peter Bright  Georgina Shuckburgh