Butterflies

The following is an extract from the article published in the 1999 Lancashire Bird Report by Simon Heyhow.

Butterflies are the most obvious and popular of our insects. As with many birds, numerous species suffered huge population declines during the twentieth century as a result of changes in agriculture, particularly loss of grasslands, and the demise of traditional woodland management.

However, we are relatively fortunate - 34 butterflies are seen regularly in Lancashire and North Merseyside. Two areas are especially important: the dune coasts of Merseyside and the Fylde, and the wooded grasslands on the Morecambe Bay limestone around Silverdale. The latter is amongst the most significant areas for butterflies in the country. Key species may be found throughout these areas but two sites are particularly important: the National and Local Nature Reserves at Ainsdale on the Sefton Coast, and Gait Barrows NNR in the north.

In 1995, The Museum of Lancashire (Fleetwood Museum) and Butterfly Conservation came together to promote the national 'Butterflies for the New Millennium’ project. Since then over 74,600 records have been collected from a wide range of sources. Historical records are being researched with a view to a Lancashire publication incorporating all available knowledge of butterflies within the county.

Further records from before 1992 would be very welcome to complete the picture from earlier years and please continue submitting all current records so we can monitor annual changes. All contributors will receive a copy of the annual butterfly and moth report. Records should be sent to:

S.J. Hayhow, Curator (Natural Sciences),
Fleetwood Museum, Queens Terrace, Fleetwood, FY7 6BT

SMALL SKIPPER Thymelicus sylvestris
This species has undergone a dramatic change in status, spreading rapidly north-west over the last decade. Previously known only in south Liverpool, it had reached the Ribble by the mid-1990s, since becoming firmly established around Burnley and Pendle and, most recently, at Heysham and the Gisburn Forest. It has been recorded in 228 tetrads.
 

Caterpillars feed on coarse grasses, mostly Yorkshire Fog, and adults are in flight from late June and throughout July.

LARGE SKIPPER Ochlodes venata
This is the most widespread of our skippers despite recent setbacks. It is mainly recorded from lowland areas in woodland edge or scrub habitats where caterpillars feed on a variety of coarse grasses. The adults emerge slightly earlier than Small Skipper.

Transect counts show a marked decline recently, with 1998 and 1999 being particularly poor years. In North Merseyside at least, this decline coincided with colonisation by Small Skippers which appear to be replacing them on some sites.

DINGY SKIPPER Erynnis tages
A nationally declining species but apparently holding its own in Lancashire. The main population is in the Silverdale area (6 tetrads) but, in the past, occasional reports have come from the south-west and the Fylde. Caterpillars feed on the leaves of Bird’s-foot Trefoil and vetches.

GRIZZLED SKIPPER Pyrgus malvae
An unauthorised introduction to Gait Barrows NNR apparently took place in 1997, when the species was also seen at Warton Crag. Small numbers reappeared at Gait Barrows into 1998 with one record in 1999.

WOOD WHITE Leptidea sinapis
This species turned up in the Silverdale area in 1997 at the same time as the Grizzled Skipper so a release seems to be the likely explanation. There were two records of probably the same individual in 1998 but no sightings in 1999.

PALE CLOUDED YELLOW Colias hyale
A southern European migrant rare in Britain and exceptionally difficult to separate from the pale form of Clouded Yellow. There are two recent records from Ainsdale NNR in 1992 and 1996.

CLOUDED YELLOW Colias croceus
This migrant species from southern Europe and north Africa is seen annually in southern Britain but remains sporadic in our area. Most records come from coastal sites but whether this reflects the distribution of butterflies or bird/butterfly-watchers is unclear.

Some years see huge influxes; the largest recent one locally was in 1992, when there were over 400 sightings in our two 'counties’ between 14 May and the beginning of October. 1992 was exceptional in national terms with far more seen in the north-west, and particularly in Northern Ireland, than the usual southern sites. A scattering of records occurred in 1996 at coastal sites such as Seaforth, Lytham St. Annes and Fleetwood but a more widespread influx took place in 1998 when at least 30 were recorded between 28 June and 7 October. There was a single record in 1999. Small numbers of the pale helice form have been seen in both recent influxes.

Clouded Yellows breed in some British summers but until very recently have been unable to survive over-winter and become established - climate change is therefore likely to bring increasing records.

BRIMSTONE Gonepteryx rhamni
A stable population is present on the Morecambe Bay limestone south to Lancaster but there are increasing reports, mostly of wandering males, from further south, particularly in the late summer months. The food-plants, Purging Buckthorn and Alder Buckthorn are native to the limestone but are increasingly being planted in country parks and conservation schemes which may see a further increase in the status of the species. Recorded from 76 tetrads.

LARGE WHITE Pieris brassicae
Widespread and common over much of the region but has declined during the 1990s. The species has been recorded from 600 tetrads with a small peak in numbers in May and a larger peak in August.

SMALL WHITE Pieris rapae
Widespread and common in a similar pattern to the Large White and also showing a slight decline. Records come from 586 tetrads with most during August.

GREEN-VEINED WHITE Pieris napi
Having not adapted to breeding on cabbage crops like other 'whites’, it is found in smaller numbers but records indicate a more even spread across the region with more records from upland areas. Recorded from 542 tetrads. Numbers have remained stable.

ORANGE TIP Anthocharis cardamines
Unlike other 'whites’, Orange Tips have just one generation per year, emerging in late April or early May to breed on Cuckoo Flower, Garlic Mustard and related plants.

Records indicate that this species shows a continued spread to areas like the Fylde where it was previously scarce or absent. It has now been found in 461 tetrads with the spring of 1996 being particularly good. 1998 and 1999 saw numbers somewhat down on previous years but there were some unusually late individuals.

GREEN HAIRSTREAK Callophrys rubi
A local species with scattered colonies across the Pennine areas, notably the West Pennine Moors and Forest of Bowland. There are also smaller populations on the remaining mosslands and the Morecambe Bay limestone areas bringing a total of 55 tetrads with records. 1998 brought several records of new colonies but reports suggest a gradual decrease during the 1990s.

PURPLE HAIRSTREAK Quercusia quercus
Because of the species tree-top habits and limited flight times, in late July to August, it is easily missed. There are still strong colonies in the Silverdale area but recent work, particularly surveys for eggs and larvae, suggest the species is probably overlooked in its oakwood habitat elsewhere. Records from the Forest of Bowland and sites on the fringes of Merseyside and Greater Manchester indicate that it may well be more numerous than the 20 tetrads on the distribution maps suggest.

WHITE-LETTER HAIRSTREAK Satyrium w-album
This species is dependent upon elm leaves as its larval food-plant. Populations were devastated by Dutch Elm Disease but it is still holding on tenuously at its traditional Ribble Valley sites. Other discoveries, such as in Merseyside and Hindburndale in 1999, hopefully indicate that the species may not be as scarce as recent records (from only four tetrads) suggest. It is another butterfly which deserves a more concerted effort to locate larvae in the spring, especially at old sites along the Ribble Valley. The adults are mostly seen during July.

SMALL COPPER Lycaena phlaeas
This active little species is widespread and reasonably common although it has seemingly declined over recent years. The first generation, in May, is often hard to connect with, but it is far more numerous in July-August. Some remain in flight well into October.

Recorded from 369 tetrads, it is most common along the coast and around the southern urban fringes. The main food plants are Common and Sheep’s Sorrel.

NORTHERN BROWN ARGUS Aricia artaxerxes
Confined to seven tetrads on the Morecambe Bay limestone, where it breeds on Common Rock-rose.

Its vulnerable status has led to its inclusion in local Biodiversity Action Plans. Poor weather has been a problem during the flight period of June to August in recent years.

COMMON BLUE Polyommatus icarus
By far the commonest and most widespread of our 'blues’, it has been recorded in 250 tetrads and can be found in grassy areas where its larval food-plant, Bird’s-foot Trefoil grows. In 1998 one site was re-colonised after an absence of several years but the last two years of the century showed a marked decline in numbers.

The species shows two seasonal peaks, in late May/early June and late July/early August, with an occasional third generation into October in mild autumns.

HOLLY BLUE Celastrina argiolus
After a boom period in the early 1990s, the species faded in mid-decade but came back in 1996 and showed up strongly in 1998 and spring 1999, although numbers were curtailed abruptly in the latter. The good season of 1998 extended from 27 March to 22 September.

It is a wandering species and was recorded from 193 tetrads during from 1992, with many records coming from gardens.

It is unusual in that the caterpillars’ food-plants vary between seasons: Holly in spring and Ivy in summer.

DUKE OF BURGUNDY Hamearis lucina
This nationally scarce species is mainly confined to Gait Barrows NNR with occasional records from adjacent sites. Gait Barrows is being actively managed to promote the species, principally through coppicing to promote Cowslips, its main larval food-plant. 'The Duke’ has responded well, despite the continued national decline. Adults are on the wing in May.

WHITE ADMIRAL Ladoga camilla
One was in a Trawden garden in 1995. This is a species which is dependent on Honeysuckle and is spreading slowly northwards nationally.

RED ADMIRAL Vanessa atalanta
A common migrant species which had an excellent year in 1995. Subsequent years also saw respectable numbers, especially during the September and October period. Some very early dates suggest adults are now surviving our recent mild winters. Records come from a total of 509 tetrads. Sightings at Seaforth suggest there is a regular southward movement in early autumn.

PAINTED LADY Cynthia cardui
A regular migrant species from southern Europe with about one good year per decade. 1996 was an exceptional year for the species. From the start of June numbers built up to produce many huge counts on suitable nectar sources, e.g. c.2000 on Sea Lavender on Pilling salt-marshes. In contrast, during 1997 the species was very scarce but a scattering of sightings followed during 1998 and 1999 bringing a total of 486 tetrads with records.

SMALL TORTOISESHELL Aglais urticae
This butterfly has been recorded from 694 tetrads, more than any other species. After a poor spell in the early 1990s the Small Tortoiseshell experienced a revival in fortunes in 1995 and 1996 before numbers tailed off again towards the end of the decade. A distinctive garden visitor, where it breeds on nettles.

The species over-winters as an adult, hibernating in buildings, tree cavities etc., and may emerge during warm spells in winter. It is almost always the first butterfly to be seen each year in our area.

LARGE TORTOISESHELL Nymphalis polychloros
A surprising record of one at Sunderland Point on 12 May 1994 was seen by a reliable observer.

CAMBERWELL BEAUTY Nymphalis antiopa
After the notable influx of 27 records between 1 August and 17 September in 1995, one was seen at Churchtown, Southport on 16 October 1999. This is another migrant species, but mostly from eastern Europe and Scandinavia. There are now 43 published records of this impressive butterfly for 'old’ Lancashire.

PEACOCK Inachis io
This attractive species is common and widespread with records from 551 tetrads. There has been a marked spread into coastal areas such as the Fylde.

Like the Small Tortoiseshell and Comma, it over-winters as an adult and a run of mild winters has led to more doing so successfully in northern areas. This is reflected in increasing numbers of spring sightings in our area. Eggs are almost always laid on nettles.

COMMA Polygonia c-album (Linnaeus)
This has been another success story of the 1990s. Previously the northern edge of its range roughly followed the line of the Mersey but it began to break through into North Merseyside during the late 1980s and has now become firmly established, moving inexorably northwards and has now been recorded in 275 tetrads.

Commas are unusual in that the two generations show distinctly different wing shapes. They may been seen in our area as early as February and as late as October, and are often found feeding on nectar sources in gardens. The main food plant of the caterpillars is nettles.

SMALL PEARL-BORDERED FRITILLARY Boloria selene
Lancashire’s breeding fritillaries are dependent upon various species of violets on which eggs are laid and caterpillars feed. In turn, violets require grassy, open woodland or scrub conditions to thrive and, as this resource has diminished, both plants and butterflies have undergone massive national declines. Management aimed at halting this decline largely consists of restoring habitat suitable for violets, mainly through re-establishing coppicing of deciduous woodlands and establishing forest rides. Recent research has pointed to the importance of bracken in encouraging the growth of violets in open habitats and suitable means of managing bracken-covered hillsides is being actively investigated.

The Lancashire population of Small Pearl-bordered is centred on eight tetrads in the Silverdale area but other small colonies are present in the north of the county with records from as far east as the Gisburn Forest. One or two sightings suggest the chance of other undiscovered colonies, maybe around Bowland.

The species has declined nationally since the 1970s but local colonies seem reasonably stable, despite poor weather during the flight period of May and June in both 1997 and 1998.

PEARL-BORDERED FRITILLARY Boloria euphrosyne
This species has suffered a drastic decline and extinctions at many English sites. Locally, it is confined to six tetrads on the Morecambe Bay limestone and is the subject of a local Biodiversity Action Plan. 1998 was a poor year locally with 40% declines on most sites. This was weather-related and it will hopefully recover although it remains vulnerable.

Adults emerge slightly earlier in May than the previous species but the flight periods of these two superficially similar butterflies overlap considerably.

HIGH BROWN FRITILLARY Argynnis adippe
Lancashire retains nationally important populations of this endangered, Red Data Book species. It survives in seven tetrads on the Morecambe Bay limestone, alongside the two previous species. It emerges later than these and most are seen during July and August.

It is at the northern edge of its range with us and, befitting a southern species, rarely flies except on the hottest of days. Numbers vary greatly between years, largely dependent upon weather conditions. 1997 saw high numbers on transect counts but the wet July and August of 1998 brought numbers down by up to 40%. However, the species is generally faring well in Lancashire and being well monitored by the High Brown Fritillary Action Group.

DARK GREEN FRITILLARY Argynnis aglaja
This species is generally found in more open conditions than the three previous species and is more associated with scrub than woodland edge.

It has been recently recorded in twelve tetrads but is only seen regularly in north Lancashire and on the Sefton Coast between Hightown and Birkdale, where it is North Merseyside’s only fritillary species.

The flight period is from late June into July.

SILVER-WASHED FRITILLARY Argynnis paphia
In recent years there has been an expansion of this attractive butterfly from the south Cumbria colony, resulting in singles at Gait Barrows in 1995, 1996 and 1998.

It is tolerant of more heavily wooded habitats than other fritillaries and it will be interesting to see whether, having gained a toehold on one site, it manages to re-colonise other areas of the county.

SPECKLED WOOD Pararge aegeria
By the late 1990s the sight of male Speckled Woods battling for display territories on sunny spots on the woodland edge had become familiar throughout much of our two counties, where it has been recorded from 194 tetrads. This colonisation has been both extremely rapid and successful, spreading from North Merseyside during the 1980s and reaching north-western Lancashire during the 1990s. Wherever it has colonised it has flourished and on many sites it is the most common species during its peak flight time of August and September.

Eggs are laid on a variety of course grasses, especially Cock’s-foot and Yorkshire Fog.

WALL Lasiommata megera
Found frequently throughout lowland parts of the region in 389 tetrads. Unlike our other large ‘browns’, Walls have two generations per year. The first emerges during May while the second, more numerous, generation can be seen from the end of July into September. 1996 was a poor year but good numbers were seen in subsequent years.

In parts of southern England it appears that the species is faring badly, with numbers declining and some local extinctions. There are no indications of such problems in our area but monitoring of populations is important.

SCOTCH ARGUS Erebia aethiops
Occasionally individuals stray over the border from the Arnside Knott colony in Cumbria. The most recent record was in 1981.

GRAYLING Hipparchia semele
Nationally, Graylings are restricted to dry areas of sparse vegetation, mostly at coastal locations. When not feeding, adults are most often seen sunning themselves on bare ground where they can be extremely difficult to spot due to their habit of keeping their wings folded.

Good numbers occur along the dunes of the Sefton Coast and at Lytham St. Annes. Also regularly reported from limestone pavement sites and at other coastal locations such as Heysham. Recorded from 34 tetrads. The caterpillars feed on a variety of grasses and the flight period is from July to September.

GATEKEEPER Pyronia tithonus
This species has remained common south and west of a line from the Wyre Estuary south-east to Preston and down to Rossendale. Outside this region there is just a scatter of records from Silverdale and east Lancashire. On favoured sites, where fine grasses such as fescues and bents, the preferred larval food plants, dominate, it is often the most numerous of all our butterflies during its single flight period of July-September.

In 1999 there were more reports from mid-Fylde, indicating an expansion of range and it has now been recorded from 196 tetrads.

MEADOW BROWN Maniola jurtina
This species is more catholic in its choice of larval food plants than Gatekeepers and is common wherever there is suitable grassland habitat, especially along the Lancashire and Merseyside coast and on limestone grassland in the Ribble Valley and north Lancashire. Records come from 558 tetrads but suggest a decline over recent years.

SMALL HEATH Coenonympha tullia
By far the smallest of our brown butterflies, the Small Heath is another grassland species reliant on fine grasses as its larval food-plants. Research in Southport showed this butterfly prefers very short grass swards containing low-growing flowers and patches of scrub.

It has a widespread distribution, being recorded in 165 tetrads, but is most common along the coast and in east Lancashire around Bowland, Burnley and Pendle.

There are usually two generations per year but these overlap and it is generally most numerous in July.

LARGE HEATH Coenonympha tullia
This wet mossland species has declined in England over recent decades due to losses of its favoured habitat. Caterpillars are dependent upon tussocks of cottongrass while the adults feed mostly on flowers of Cross-leaved Heath.

However, it is found in good numbers at its two remaining Lancashire sites. A 1999 survey of the Bowland site by Butterfly Conservation found the colony over a wider area than was previously known. Regular monitoring is still required and the species has suffered from collecting at other sites so these must still be regarded as vulnerable populations.

MONARCH Danaus plexippus
One was seen at Fleetwood Docks on 3rd May 1999. The date suggests it was probably of dubious origin or maybe ship-assisted. There are three previous published records, in 1933, 1950 and 1968.