News and information about wildlife in and around the parish

Butterfly of the Week 10th June 2020

  

Marbled White: This unmistakeable butterfly of unimproved tall grass grasslands, is found all across the Mendips and has, in the past been seen on Broadhay. Its black and white chequered pattern and name, as a ‘white’, obscures the fact that it is a ‘brown’! It is about the same size as a meadow brown which are themselves particularly abundant this year both in fields and even into gardens. Like the other browns, Meadow, Hedge, Ringlet and Small heath its caterpillars are grass feeders. The adults emerge from their pupae from mid-June and adults can be seen until the end of July. Once mated the female scatters her eggs amongst suitable grasses. When the eggs hatch the first stage larvae goes straight into hibernation buried deep in a grass tussock. In the following year in late January or early February, the larva starts to feed then moults, then feeds and moults two more  times. Each time the caterpillar transfers to increasingly coarse grasses before pupating at the end of May or beginning of June. There is, thus, only one generation each year. When walking on Mendip keep a good look out for them and you may notice that they have a special fondness for purple flowers like knapweed and scabious where they are easy watch and to photograph. The females have a yellowish front edge of the fore-wings and this yellowness also shows on their undersides.

Photos    Peter Bright

Two Westbury Grassland Butterflies of the Week 3rd June 2020

 

 

Meadow brown: The Meadow brown is probably our commonest butterfly and is on the wing from the beginning of June through to September or even October if the weather is kind. It is quite a large brown butterfly being a bit smaller than a large white. The females are larger than the males and have conspicuous orange patches on the forewings whereas the males look generally darker and have an area of dark scent scales on the upper surface of their forewings that produce pheromones that encourage the females to mate. They can be abundant in grassland that is not too heavily grazed as well as along roadside verges, the edges of woodland rides and anywhere else with a good mix of grasses maybe up to 50cm high. Eggs are laid singly amongst the grasses and may even be scattered. The young caterpillars feed on the finer grass species like fescues and the older caterpillars move on to more robust species like cock’s foot and wood false brome. They overwinter as caterpillars hidden deep in suitable grass tussocks. During the following spring they start feeding again and pupate in late April and onwards depending on the size of caterpillar they overwintered as. Males will fly quite long distances seeking out unmated females that are ‘seduced’ by showers of pheromones. Mating can last for up to an hour when the pair can be seen resting amongst grasses. If disturbed the female can fly with male still attached to a new resting spot. The female soon begins egg laying and it is these eggs that produce the caterpillars that will spend the winter in a grass tussock. There is just one generation each year.

Photos Tina Westcott   Peter Bright

 

  

Small heath: This little butterfly is a ‘brown’ like its relative the meadow brown but is only the size of a common blue. Its caterpillars feed on fine grasses like fescues that abound in dry, shallow soiled, unimproved short sward grassland like that found on the top of Mendip. Westbury Beacon, Cook’s Field and Deerleap are good habitat. It is hardly surprising that it has barely appeared in Westbury gardens in our regular weekly recordings. It overwinters as a caterpillar in various stages of maturity depending on when winter comes. The largest of these caterpillars will pupate in early spring to appear as the first small heaths of the year in early May. The smaller caterpillars will take longer to grow and then pupate to produce the later butterflies of this first brood. These adults then mate to produce eggs leading to a second generation on the wing in late July and August. Their eggs will become the caterpillars that will over winter to emerge in the following spring. This small butterfly, itself, shows orange when it flies showing the orange upper surfaces of its wings but when it settles – always with its wings closed, all you see is the grey brown underside of the hind wing and a small flash of orange from the underside of the forewing. This frequently disappears as it folds its forewings further and it can almost disappear against the browns and greys of its preferred dry grassy habitat. In can increase the effectiveness of this camouflage by holding its wings at such an angle that they do not cast a shadow.

Photos   Oliver Halls   Peter Bright

Four-spotted chaser

Another frequent visitor to garden ponds, recently arrived. The number of wing spots clearly distinguishes it from the otherwise similar but much rarer female Scarce Chaser, which only has dark spots at the wing tips. Male scarce chasers are blue, but both sexes of the four-spotted chaser are identical and thus virtually impossible to tell apart.

Butterfly of the Week 27th May 2020

   

Small tortoiseshell: This familiar butterfly hibernates as an adult in September or October in sheltered places in woodlands and woodpiles or in our garages, barns, lofts, and church rooves, where its dark shape, with antennae folded back, can be a familiar sight. On sunny days in January or February they may wake and fly for a short while but soon return to hibernation. In March, as it warms up, they leave hibernation and seek mates and suitable patches of nettles. They are quite fussy about the choice of location and the growth stage of nettle patches. These butterflies are strong fliers and may travel a 100 or more miles in their lifetime. Many are somewhat migratory in that the spring and early summer adults fly generally NNW and the second generation from mid-August fly approximately SSE. There are influxes from the continent each year, but it is believed that most small tortoiseshells are ‘homegrown’ unlike red admirals and painted ladies. After mating the female lays several batches of 60-100 eggs on the undersides of young nettle leaves. The caterpillars hatch quite soon and feed communally and build a somewhat protective web. Once that bit of nettle is eaten out the larvae will move on and spin a new web. When ready to pupate, they will wander away from the nettle patch or find a suitably sheltered spot within it, to form their suspended pupae. In less than a month adult butterflies emerge – which is happening here and now at the end of May! Most in our part of the world go on to find mates and lay eggs which will become the second generation. These are the butterflies we see on our Buddleia and Michaelmas daisies in the autumn. They are feeding up on nectar before finding hibernation sites in September or October to pass the winter. A few of this first generation may go straight into an early hibernation as they would nearly all do in Scotland. Small tortoiseshells are nowhere near as abundant as they used to be, particularly in the south of England. The reasons for this are rather unclear but climate change may have favoured a tachinid fly that lays its eggs on the nettle leaves that get eaten by young caterpillars. These eggs then hatch inside the caterpillar and eat it out from the inside without killing it until the fly’s development is complete when it leaves the dead caterpillar to form its own pupa, from which comes a new fly. Other circumstances, like the summer drought of 2018, have meant there were few suitable nettles for this first generation to lay eggs on in June to provide the second generation that are the autumn butterflies that will go into hibernation. If the season becomes really advanced many may try for a third generation which fails completely because suitable nettles and nectar sources are not available. The factors affecting how many small tortoiseshells there are in our gardens, and in the wider countryside, from year to year, are clearly complicated.

Photos: Mick Fletcher, John Ball, Peter Bright

Cream-spotted tiger moth

A local, mostly southern species that usually flies at night but, as in this case, can be diurnal immediately after emergence. Second year running in our garden.

Butterfly of the Week 20th May 2020

 

Red Admiral: This spectacular butterfly probably got its name from the ‘royal navy ensign colours’ of its wings rather than being a corruption of ‘admirable’ which it also undoubtedly is! It is a butterfly which traditionally did not survive British winters and so our butterflies came in several waves of immigration – first from North Africa and Southern Europe, then from Spain and Portugal and lastly from Eastern Europe. The offspring of the butterflies that came to the UK do, to some extent, head back south again. The variable numbers of this butterfly in the UK each year reflects the size of these several immigrations. With milder winters it may be that there will be some homegrown butterflies as they can be seen flying in any month of the year. Unlike Peacocks and Small Tortoiseshells, they do not go into proper winter torpor for hibernation. It maybe that caterpillars and pupae can also survive our winters in increasing numbers, which provide some of the early butterflies seen in March and April. The main food plant is stinging nettle and eggs are laid singly on the top surfaces of suitable nettle leaves. The caterpillar constructs a tent out of the leaf so remains hidden for its whole life. New tents are made as it grows and finally forms the pupa inside a tent made from a folded nettle leaf. Do try looking for them on nettles. There are no distinct generations with so many immigrants coming in widely variable numbers throughout the summer, but all the life stages can be found in most months of the year. In autumn they can be seen feeding up on the sugars in ivy flowers or rotting fruits before heading south. There is considerable interest in just how much they are now overwintering in the UK successfully, so records in December and January would be particularly interesting.

Photos   John Ball    Robert Maxwell Wood

Butterfly of the Week 13th May 2020

 

 

Brimstone: That this butterfly is the origin of the word ‘butter-fly’ with its abundance and colour, flying early in the year, is a lovely story. Brimstones over-winter as adults in woodland and hedgerow places such as amongst ivy. They can appear at any time in January or February flying on warm sunny days but will inevitably return to hibernation. They emerge properly in late March and April and will wander widely in search of mates, and for the females, in search of purging buckthorn around Westbury and alder buckthorn in parts of the country with more acidic soils. The males are bright yellow and unmistakeable, while the females are a much paler greenish cream colour – resembling large whites in colour and size. However, once they settle, with wings always closed, the lack of black wingtips and the pointed shape of the wings make them easy to recognise. Having found a suitable buckthorn shrub, the female will flutter around until exactly the right places have been found and then lay one egg in each of them. These eggs hatch to produce a green caterpillar which can be found quite easily by looking closely at the leaves of a buckthorn bush. The pupa is formed on the underside of a leaf and has the appearance of a folded leaf. By the end of June the adults that flew in April and May will have died and during July and August the new generation of adults will have emerged from their pupae and will be feeding up on nectar from flowers, often purple or blue, such as knapweed and buddleia, before going into hibernation for the winter. There is just this one generation a year.

Photos Peter Bright

Azure blue damselfly

Another species to emerge this month, the Azure Blue damselfly is more often met with in garden ponds than the Common Blue, which prefers large ponds and lakes. Not easy to distinguish, but the Azure Blue has blue shoulder stripes narrower than the black lines below them, unlike the Common Blue. This is a male, the females are usually more greenish on the back.

Butterflies of the Week 6th May 2020

  

          

Large and Small whites:  These are the ‘Cabbage Whites’ that are a gardeners’ nightmare. There are two separate species the Large and the Small. They both over-winter as pupae formed at the end of August or beginning of September and emerge in April the following Spring.

The Large White lays eggs in batches, particularly on the leaves of domestic Brassicas, up to 150 at a time. They hatch into caterpillars that feed particularly on the outer leaves of ‘cabbages’ and, being so exposed, their bold black and yellow colouring indicates to predators their unpalatability. There is some help for gardener’s in the form of the ichneumon wasp, Cotesia glomerata. These wasps lay between 15 and 80 eggs into young large white caterpillars. These wasp larvae feed on the caterpillar’s fat reserves without killing it and finally, when fully grown, break out of the now dead caterpillar forming a collection of yellow cocoons around the corpse.

The Small White lays its eggs singly and the caterpillars move onto the underside of leaves in the heart of the plant doing considerable damage. Being green in colour and being on the underneath of leaves makes them well camouflaged. In the same way as for the large white there are a variety of parasitic wasps (including Cotesia rubecula) that lay eggs inside young caterpillars.

To tell these whites apart look at the front edge of the forewings. In the Large White it goes all the way around the point of the wing as unbroken black. In the Small White the black is almost entirely on the front edge of the wing. Large White females and males and females of Small Whites have two more or less conspicuous black spots on the upper surface of the forewing. Male Large Whites have no such spots. Generally, the Large Whites are distinctly larger than the Small Whites, but they can each vary being extra small or large in size. You might think of Large Whites as being Peacock sized and Small Whites as being Small Tortoiseshell sized.

For both these Whites there are 2 generations each year with the butterflies flying in April and May laying eggs that become the butterflies flying in July and August whose eggs will go on to produce the overwintering pupae.

Photos   Peter Bright   Mick Fletcher

 

Broad-bodied chaser

Male broad-bodied chaser (females are brown), the second of our damsel & dragonflies to appear in spring. Males patrol ponds and aggressively chase way other males that appear.