News and information about wildlife in and around the parish.
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