Pearl-bordered Fritillary

Boloria euphrosyne (boh-LOR-ee-uh you-froz-SY-nee)

Pearl-bordered-Fritillary- 5D37078 Wyre Forest May 2012
Photo © IainLeach
 

Wingspan
Male: 38 - 46mm
Female: 43 - 47mm

Checklist Number
59.014

Family:NymphalidaeRafinesque, 1815
Subfamily:HeliconiinaeSwainson, 1827
Tribe:ArgynniniSwainson, 1833
Genus:BoloriaMoore, 1900
Subgenus:ClossianaReuss, 1920
Species:euphrosyne(Linnaeus, 1758)

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Introduction

This woodland butterfly gets its name from the series of "pearls" that run along the outside edge of the underside of the hindwing. Males are often seen flying swiftly, low across the breeding site in search of a mate and are extremely difficult to follow, the colouring of the wings providing excellent camouflage against the dead bracken that is often found at these sites. The Pearl-bordered Fritillary may fly with the Small Pearl-bordered Fritillary at certain sites, although the Pearl-bordered Fritillary, which emerges a couple of weeks before the Small Pearl-bordered Fritillary, generally appears much paler in colour as a result.

In England and Wales this butterfly in scattered and isolated colonies south-west of a line running between Denbighshire in the north-west to East Kent in the in south-east. There are also colonies in Westmorland and West Lancashire. It is also widespread in central Scotland, but very local or absent in the north and south of the country. In Ireland it is found in the Burren limestones of Clare and South-east Galway. It is absent from the western and northern Isles of Scotland, the Isle of Man and the Channel Islands. This butterfly forms discrete colonies which vary wildly in numbers, from a couple of dozen to over a thousand, this being largely-determined by the availability of suitable habitat. Most colonies contain a few dozen adults.

Boloria euphrosyne

This species was first defined in Linnaeus (1758) as shown here (type locality: Europe and north America).

Pearl-Bordered Fritillary - imago - Bentley Wood - 10-May-06 (0080)

Male
Photo © Pete Eeles

Pearl-bordered-Fritillary Bentley wood 30 April 2011- 03C0609

Male Underside
Photo © IainLeach

Pearl-bordered Fritillary female - Wyre Forest 01.06.2013

Female
Photo © Neil Freeman

Pearl-bordered-Fritillary-Bentley Wood 15 May 2010  I9T7510

Female Underside
Photo © IainLeach

Photo Album ...


History

The table below shows a chronology of vernacular names attributed to this species. Any qualification of the name (e.g. male, female) is shown in brackets after the name.

YearNameReference
1699April FritillaryPetiver (1695-1703)
1717April Fritillary with Few SpotsPetiver (1717)
1766Pearl Border FritillariaHarris (1766)
1824Pearl-bordered FritillaryJermyn (1824)
1832PrinceRennie (1832)
1959Large Pearl-bordered FritillaryHeslop (1959)

Conservation Status

Once considered common and widespread, the Pearl-bordered Fritillary is now one of our most-threatened species. The cessation of coppicing which resulted in the loss of suitable habitat is believed to be one of the major causes of this drastic decline. Conservation efforts have therefore focused on habitat management and there have been a number of success stories. However, this butterfly is still declining and, as such, continues to be a priority species for conservation efforts.

UK BAP StatusOccurrence Change
1976-2014 (%)
Abundance Change
1976-2014 (%)
Occurrence Change
2005-2014 (%)
Abundance Change
2005-2014 (%)
Priority Species
Click here to access the Biodiversity Action Plan (BAP) for this species.
Large Decrease-95
Large Decrease-71
Stable+3
Increase+45

The table above shows the occurrence (distribution) and abundance (population) trends, using information from The State of the UK's Butterflies 2015 (Fox, 2015). Any UK BAP status is taken from the UK Biodiversity Action Plan (UK BAP) (2007 review).

Habitat

This butterfly is typically found in deciduous woodland containing open areas, such as woodland clearings, that provide the right conditions, foodplants and nectar sources for this species to thrive. This butterfly can also be found in conifer plantations and limestone pavements in some areas. Sites are generally suitable 2 to 4 years after a woodland clearing has been formed, when the foodplants and nectar sources are optimal for this species. However, these sites can quickly become overgrown and, unless there is suitable habitat nearby, colonies will tend to die out.

Distribution

 

Click here to see the distribution of this species or here to see the distribution of this species together with specific site information overlaid.

Life Cycle

This is the earliest of our fritillaries to emerge. In good years, the butterfly emerges at the end of April in the south - this butterfly once being known as the "April Fritillary" as a result. Most adults emerge at the start of May, but may not appear until the end of May in more northern sites. In exceptional years, there may be a partial second brood at some southern sites, with adults emerging in August.

The chart(s) above have been correlated with the phenology plot below, taken from the UK Butterfly Monitoring Scheme. The blue line gives average counts over the full data set from 1976 to date, and the red line gives the average for the last year.

 

Imago

Males start their day by nectaring on various flowers, such as those of Bugle, Dandelion, Bird's-foot Trefoil and Buttercup, before patrolling low over the breeding sites in search of a mate, investigating any reddish brown object encountered. When a virgin female is found, the female will fly to a suitable platform, sometimes at some height, where the two mate, staying together for 30 to 60 minutes. Egg-laying females are relatively-easy to follow in flight as they flutter slowly and deliberately low down over vegetation, searching out suitable patches of foodplant on which to lay.

Adults feed primarily on Bugle (Ajuga reptans). Bird's-foot Trefoil (Lotus corniculatus), Bluebell (Hyacinthoides non-scriptus), Buttercups (Ranunculus spp.), Dandelion (Taraxacum agg.), Hawkweeds (Hieracium/Hypochoeris), Ragged Robin (Lychnis flos-cuculi), Selfheal (Prunella vulgaris), Thistles (Cirsium spp. and Carduus spp.) and Tormentil (Potentilla erecta) are also used.

Boloria euphrosyne

Pearl Bordered Fritillary - Wyre Forest - 30th May 2012

Photo © Nigel Kiteley
30-May-2012

Pearl-bordered Fritillary

Photo © Gwenhwyfar
03-May-2010

Pearl-Bordered Fritillary - imago - Bentley Wood - 01-May-09 (3)

Photo © Pete Eeles
01-May-2009

Pearl-bordered Fritillary (male), West Sussex (16 May 2013)

Photo © Mark Colvin

Pearl-Bordered Fritillary - imago - Bentley Wood - 11-May-04 (3)

Photo © Pete Eeles

Pearl-bordered-Fritillary-Bentley Wood 15 May 2010  I9T5796

Photo © IainLeach

Pearl-bordered Fritillary - imago - Bentley Wood - 22-May-13-12

Photo © Pete Eeles

Pearl-bordered Fritillary pair, Seaton, Cornwall. 19 April 2015.

Photo © essexbuzzard
19-Apr-2015

Pearl-bordered-Fritillary- 5D35488. N Yorks May 2015

Photo © IainLeach

Pearl-bordered-Fritillary- 5D34842 Wyre Forest May 2012

Photo © IainLeach

peal-bordered Frit 2010  GR

Photo © Gruditch
01-May-2010

Pearl-bordered Fritillary - imago - Bentley Wood - 21-May-10 (1)

Photo © Pete Eeles
21-May-2010

Pearl-Bordered Fritillary - imago - Bentley Wood - 11-May-04

Photo © Pete Eeles

Pearl-bordered Fritillary Basking - Mabie Forest, Dumfriesshire - 12th May 2012

Photo © Graham Beckwith
12-May-2012

Pearl-bordered-Fritillary- 5D36445 Wyre Forest May 2012

Photo © IainLeach

Pearl-bordered Fritillary - Rewell Wood, Sussex 27-April-2012

Photo © Neil Hulme
27-Apr-2012

Pearl-bordered-Fritillary- 5D36144 Wyre Forest May 2012

Photo © IainLeach

Pearl-bordered Fritillary - imago - Bentley Wood - 22-May-13-8

Photo © Pete Eeles

Pearl-bordered-Fritillary- 5D37341 Wyre Forest May 2012

Photo © IainLeach

Pearl Bordered Fritillary Male - Abbots Wood, Sussex 22-April-09

Photo © Vince Massimo
22-Apr-2009

Photo Album (75 photos) ...


Ovum

Eggs are generally laid singly on the underside of a leaf of the foodplant, but may be laid on nearby vegetation. The egg is yellow when first laid, turning grey prior to the larva emerging. This stage lasts around 2 weeks.

"Eggs laid on June 3rd, 1890, hatched on June 18th, remaining in the egg state fifteen days. A large number of eggs were deposited during the first week of May, 1893, which hatched the following week owing to the continuous hot weather. The eggs are laid singly on the leaves and stems of the dog violet (Viola canina). The egg is 0.8 mm. high, of a conical shape. The micropyle is sunken and finely pitted, it is keeled longitudinally; these vary in numbers, but usually average about twenty-five, and are irregularly formed; some rise at the summit and run down the entire length, widening apart at various distances, where others commence and run to the base. Round the crown the keels meet, forming a zigzag brim of triangular points. The spaces between the keels are very irregularly ribbed transversely. When first laid the egg is of a greenish-ochreous-yellow, becoming paler yellow afterwards, and finally whitish-ochreous, with a dark leaden-grey crown caused by the black head of the larva showing through the shell." - Frohawk (1924)

Pearl-Bordered Fritillary - ovum - nr Stockbridge Down - 11-May-07 (1)

Photo © Pete Eeles
11-May-2007

Pearl-bordered Fritillary - ovum - Nr Stockbridge Down - 21-May-10 (1)

Photo © Pete Eeles
21-May-2010

Pearl Bordered Fritillary egg. 27/4/2012. Abbotts Wood, Sussex.

Photo © badgerbob
27-Apr-2012

PBF ovum 16-May-2014

Photo © Tony Moore
Eyarth Rocks. 15.05.14.
16-May-2014

PBF ovum

Photo © Tony Moore
Eyarth Rocks. 15.05.14.
19-May-2014

Pearl-bordered Fritillary ovum - Abbot's Wood, Sussex 9-May-2015

Photo © Neil Hulme
09-May-2015

Pearl-bordered Fritillary - ovum - Bentley Wood - 12-May-15-21

Photo © Pete Eeles
13-May-2015

Pearl-bordered Fritillary - ovum - Bentley Wood - 23-May-15

Photo © Pete Eeles
23-May-2015

Photo Album (8 photos) ...


Larva

Larvae feed by day and generally rest in leaf litter, but can also be found, especially after hibernation, basking on dead bracken. Larvae will eat whole leaves, leaving just the stem intact. They will also feed on only the leaf lobes, at the base of the leaf, leaving characteristic feeding damage that can give away the presence of a nearby larva. After moulting for the third time the larva enters hibernation, generally in a dried leaf, emerging in the spring to complete its growth. There are 4 moults in total.

The primary larval foodplant is Common Dog-violet (Viola riviniana). Heath Dog-violet (Viola canina) and Marsh Violet (Viola palustris) are also used.

Pearl-Bordered Fritillary - larva - Thatcham - 16-Jul-08 (1) {REARED}

Photo © Pete Eeles
16-Jul-2008

Pearl-Bordered Fritillary - larva - Thatcham - 18-Jun-11 (22) {REARED}

Photo © Pete Eeles

Pearl-bordered Fritillary - larva - Stockbridge Down - 17-Jun-15

Photo © Pete Eeles
17-Jun-2015

Photo Album (3 photos) ...


1st Instar

"The larva directly after emergence measures 1.4 mm. long. The ground colour is light ochreous-yellow. The fourth, sixth, eighth and tenth segments are much blotched with brown, giving the larva a banded appearance; the anal segment is also brownish. There are longitudinal rows of dark shining warts, each bearing a long, curved, serrated hair, all curving forwards; the largest are those on the dorsal surface, the lateral hairs are placed close together and are smaller. The head is shining black and hairy. The body is very finely granulated and shining. The legs are black and the claspers are ochreous. When about seven days old it measures about 3.2 mm. long, and is then of a greenish-ochreous hue. The young larva is very active, crawling with rapidity, and feeds by day upon the youngest leaves. The first stage occupies about ten days." - Frohawk (1924)

Pearl-bordered Fritillary - larva - Stockbridge Down - 01-Jun-15

Photo © Pete Eeles
01-Jun-2015

Photo Album (1 photos) ...


2nd Instar

"Before second moult it measures 6.3 mm. long. The colour is ochreous, with six longitudinal rows of black spines, each furnished with bristles; a medio-dorsal pale grey stripe bordered by a dull orange band, and a light lateral stripe; the sub-spiracular spines have pale ochreous bases; the ventral surface and claspers are brown; the legs black. The head is shining black and covered with bristles." - Frohawk (1924)

Pearl-bordered Fritillary (early instar B) reared - Caterham, Surrey 28-June-2012

Photo © Vince Massimo
28-Jun-2012

Pearl-bordered Fritillary (early instar B) reared - Caterham, Surrey 28-June-2012

Photo © Vince Massimo
28-Jun-2012

Pearl-bordered Fritillary (early instar B) reared - Caterham, Surrey 19-June-2012

Photo © Vince Massimo
19-Jun-2012

Photo Album (3 photos) ...


3rd Instar

"After second moult the ground colour is dark smoky-grey, almost black, with a paler grey medio-dorsal stripe and a checkered grey lateral stripe; all the spines, the head, legs and claspers are shining black; the spines are beset with a number of sharply pointed bristles." - Frohawk (1924)

Pearl-bordered Fritillary (early instar B) - reared Caterham, Surrey 9-July-2012

Photo © Vince Massimo
09-Jul-2012

Photo Album (1 photos) ...


4th Instar

"After third moult and shortly before hibernation it attains the length of 10.5 mm. The colour is dark purplish-brown speckled with greyish-white, forming a lateral stripe, with a fine double medio-dorsal whitish line. The head, spines and legs are intensely black and shining; the former is furnished with rather long black hairs. The ventral surface is pale tawny-brown. During the end of July, after the third moult, the larva entered into hibernation, usually selecting for the hibernaculum the dead, crumpled-up leaves, settling down on the under side and generally two or more close together. During hibernation the larva becomes greatly contracted, measuring only 6.3 mm. long, which is only about half the length before hibernating. Those plants which were most subjected to the cold and wet appeared most suitable for the health of the larva, as they produced the greatest number of survivors. A brood of larvae which hatched from eggs during the second week of May passed through the third moult in the first week of June; by the middle of June they all stopped feeding and entered into hibernation, although at times they were subjected to very high temperatures, and some were kept in a temperature rising as high as 100 degrees during several days, but they persistently hibernated, only a very few fed at short intervals during hot sunshine. On March 15th, 1892, a plant of V. canina was examined on which a few larva settled for hibernation at the end of the previous July; one was noticed in a semi-torpid condition. The shade temperature that day being 41 degrees Fahr., after a continued frost for two weeks, the comparative warmth evidently roused it from its winter sleep. On placing the larva upon another plant, which had thrown up a few young leaves, it soon straightened itself out and crawled slowly and then rested; it still remained in a somewhat contracted state, measuring only 8 mm. long. The following day, March 16th, being much warmer, with a shade temperature of 52 degrees Fahr., the larva became much more active; it had then attained 9.5 mm. in length. The four following days the plant was placed in the sunshine, but the larva apparently did not feed, as no portion of the leaves had been eaten; on the 21st, however, a small semi-circular piece was eaten out of one of the leaves, and the larva rested in a horizontal attitude on a stem in the centre of the plant in the sun's rays, which it evidently enjoyed; during the next two weeks it fed and increased in size to 12.7 mm. in length." - Frohawk (1924)

5th Instar

"The fourth moult took place early on April 7th; it rested until midday, and then became very active, gliding rapidly along, swaying its head from side to side while crawling. After fourth and last moult, 324 days old, fully grown, it measures from 22.2 mm. to 25.4 mm. long. It tapers slightly towards the head. The ground colour of the dorsal surface is black, and that of the ventral surface smoky-brown; the whole of the surface above the spiracles is freckled with indistinct greyish markings, principally near the segmental divisions and bordering on the central deep black longitudinal line, and the whole surface is speckled with extremely minute whitish dots; from the centre of each speck is a minute black hair, these form the majority of the dorsal freckles; there is a broad checkered black and white spiracular band which is unbroken on the first three segments. There are six longitudinal rows of rather short, conical, but sharply pointed spines or tubercles, each with a number of finely pointed bristles; the dorsal rows, from the first to tenth segments inclusive, have the basal half of the tubercles bright lemon-yellow, the apical half black; all the remaining tubercles are black; the anal segment has only four spines. The two first spines of the sub-dorsal series are placed on the segmental divisions. The head is shining bronze-black and covered with fine bristles of various lengths. The legs are shining black, the claspers black, with drab-coloured feet. The whole surface is granulated, being covered with very minute shining black points; the skin is smooth and of a bluish-grey colour at the segmental divisions. The larva vary respecting the colouring of the dorsal spines, in some they are wholly black, and in others only slightly yellow. It feeds at intervals during the day and rests away from the plant at night. The larva described remained in the last stage from April 7th until May 24th (forty-six days) and from the time of hatching to pupation it occupied 330 days. It pupated on May 24th and the imago emerged June 2nd, 1893, remaining only nine days in the pupal state. Other larvae which hibernated in July, 1892, commenced feeding after hibernation about March 20th, 1893, and the first one moulted last time April 10th and pupated April 25th, being only fifteen days in last stage, due to the exceptional warmth of that spring, and the imago emerged May 14th." - Frohawk (1924)

002 [Bob Eade]

Photo © Bob Eade

003 [Bob Eade]

Photo © Bob Eade

Pearl Bordered Fritillary larva. Abbotts Wood. Sussex. 6/4/2011.

Photo © badgerbob
06-Apr-2011

Pearl-Bordered Fritillary - larva - Hampshire - 04-Apr-12

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 04-Apr-12-1

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 04-Apr-12-2

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 27-Mar-12

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 27-Mar-12-1

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 27-Mar-12-2

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 27-Mar-12-3

Photo © Pete Eeles

Pearl-Bordered Fritillary - larva - Hampshire - 27-Mar-12-4

Photo © Pete Eeles

Pearl Bordered Fritillary larva. 24/4/2013. Abbotts Wood, Sussex.

Photo © badgerbob
24-Apr-2013

Pearl Bordered Fritillary larva. 24/4/2013. Abbotts Wood. Sussex.

Photo © badgerbob
24-Apr-2013

Pearl-bordered Fritillary larva (5th instar) - Rewell Wood, Sussex 27-Mar-2014

Photo © Neil Hulme
27-Mar-2014

Pearl-bordered Fritillary larva (5th instar) - Rewell Wood, Sussex  27-Mar-2014

Photo © Neil Hulme
27-Mar-2014

Pearl-bordered Fritillary - final instar larva - Thatcham - 12-May-16 [REARED]

Photo © Pete Eeles
12-May-2016

Pearl-bordered Fritillary larva (5th instar) - Abbot's Wood, Sussex 1-April-2017

Photo © Neil Hulme

Pearl-bordered Fritillary larva (5th instar) - Abbot's Wood, Sussex 1-April-2017

Photo © Neil Hulme

Photo Album (18 photos) ...


Pupa

The pupa is formed low down in vegetation, suspended head down and attached by the cremaster. This stage lasts around 3 weeks.

"The pupa measures 14 mm. long. Lateral view: The head is slightly beaked in front; the thorax keeled and angular, deeply sunken at the waist; the abdomen rises and, after running fairly straight, curves abruptly to the extremity, contracting the under surface; the wings are greatly swollen near the apex, forming a strong curve towards the abdomen. Dorsal view: Head broad, with two lateral horns; base of the wings with angular projections, sunken at the waist. The abdomen is swollen across the middle, then tapering to anal extremity. There are two dorsal rows of short, conical points; these are small and rounded on the thorax, small on the first two abdominal segments, large and prominent on the third segment and smaller on the following segments, those on the sixth and seventh segments being united by a V-shaped ridge. The ground colour is light ashen-grey and pinkish-grey, very finely reticulated with red-brown of different depths; the dorsal points are sienna-red; the antenme are checkered with white and brown; the wings have a marginal and sub-marginal row of whitish dots on each nervure. It is of the lightest colouring on the dorsal surface, which is of a pinkish hue. The pupa is suspended by the cremastral hooks to a pad of silk spun upon a leaf or stem." - Frohawk (1924)

Pearl Bordered Fritillary Pupa case. Abbotts Wood, Sussex. 5/5/2010

Photo © badgerbob
05-May-2010

Pearl-Bordered Fritillary - pupa - Hampshire - 04-Apr-12

Photo © Pete Eeles

Pearl-bordered Fritillary - pupa - Hampshire - 22-Apr-12

Photo © Pete Eeles

Pearl-bordered Fritillary - pupa - Thatcham - 16-May-16 [REARED]

Photo © Pete Eeles
16-May-2016

Photo Album (4 photos) ...


Aberrations

Description to be completed.

Click here to see the aberration descriptions and images for this species.

Similar Species

Small Pearl-bordered Fritillary

The Pearl-bordered Fritillary and Small Pearl-bordered Fritillary are most easily distinguished by their undersides. Both species have a row of 7 white "pearls" running along the edge of the hindwing (hence their vernacular names). However, the remainder of the underside of the hindwing is quite different. The Pearl-bordered Fritillary exhibits 2 very distinct additional "pearls", whereas the Small Pearl-bordered Fritillary has a mozaic of white, oranges and browns and, as such, has the more colourful underside.


Pearl-bordered Fritillary (left) and Small Pearl-bordered Fritillary (right)

It is much more difficult to distinguish Pearl-bordered Fritillary and Small Pearl-bordered Fritillary based on their uppersides. However, there are two general differences. The first is with regard to the row of chevrons at the edge of the forewings. In the Pearl-bordered Fritillary, these chevrons are often "floating" and not attached to the outer margin, whereas these chevrons are attached to the edge of the forewing in the Small Pearl-bordered Fritillary. The second is with regard to the row of spots found next to these chevrons. In the Pearl-bordered Fritillary, each of these spots is positioned midway between neighbouring markings. In the Small Pearl-bordered Fritillary, the dots are not midway, but distinctly closer to the chevrons.


Pearl-bordered Fritillary (left) and Small Pearl-bordered Fritillary (right)

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The following links provide additional information on this butterfly.

References

The species description provided here references the following publications:

ReferenceDetails
Frohawk (1924) Frohawk, F.W. (1924) The Natural History of British Butterflies.
Harris (1766) Harris, M. (1766) The Aurelian. Edition 1.
Heslop (1959) Hislop, I.R.P. (1959) A new label list of British macrolepidoptera. Entomologist's Gazette.
Jermyn (1824) Jermyn, L. (1824) The Butterfly Collector's Vade Mecum: or a Synoptical Table of English Butterflies.
Linnaeus (1758) Linnaeus, C. (1758) Systema Naturae. Edition 10.
Moore (1900) Moore, F. (1900) Lepidoptera indica.
Petiver (1695-1703) Petiver, J. (1695-1703) Musei Petiveriani centuria prima-decima, rariora naturae continens.
Petiver (1717) Petiver, J. (1717) Papilionum Britanniae Icones.
Rafinesque (1815) Rafinesque, C.S. (1815) Analyse de la nature ou Tableau de l'univers et des corps organisés.
Rennie (1832) Rennie, J. (1832) A conspectus of the butterflies and moths found in Britain, with their English and systematic names, times of appearances, sizes, colours, their caterpillars, and various localities.
Reuss (1920) Reuss, T. (1920) Die Androconien von Yramea cytheris Drury und die nächststehenden analogen Schuppenbildungen bei Dione Hbn. und Brenthis Hbn. (Lep.). Entomologische Mitteilungen.
Swainson (1827) Swainson, W. (1827) A Sketch of the Natural Affinities of the Lepidoptera Diurna of Latreille. The Philosophical magazine : or Annals of chemistry, mathematics, astronomy, natural history and general science.