Black Hairstreak

Satyrium pruni (sa-TI-ree-um PROO-ny)

Black Hairstreak - imago - Thatcham - 28-Jun-13 (3) [REARED]
Photo © Pete Eeles
 

Wingspan
Male: 34 - 39mm
Female: 35 - 40mm

Checklist Number
61.007

Family:LycaenidaeLeach, 1815
Subfamily:TheclinaeButler, 1869
Tribe:EumaeiniDoubleday, 1847
Genus:SatyriumScudder, 1876
Subgenus:  
Species:pruni(Linnaeus, 1758)

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Introduction

The Black Hairstreak is one of our rarest butterflies and one of the most recently discovered, due to the similarity with its close cousin, the White-letter Hairstreak. This species was first discovered in the British Isles in 1828 when a Mr. Seaman, an entomological dealer, collected specimens from one of the most famous sites for this species - Monk's Wood in Cambridgeshire. These were thought to be specimens of the White-letter Hairstreak until Edward Newman, a Victorian entomologist of note, declared them to be Black Hairstreak.

This butterfly is not a great wanderer and an entire colony will often confine itself to a single area within a wood, despite there being suitable habitat nearby. The inability to colonise new areas at a pace in balance with habitat loss may partially explain the scarcity of this species. This butterfly has a very restricted distribution that follows a line of clays between Oxfordshire in the south-west and Cambridgeshire in the north-east.

Satyrium pruni

This species was first defined in Linnaeus (1758) as shown here (type locality: Not stated).

Male

Black Hairstreak - imago - Thatcham - 24-Jun-13 (2) [REARED]

Male Underside
Photo © Pete Eeles

Female

Black Hairstreak - imago - Thatcham - 24-Jun-13 (7) [REARED]

Female Underside
Photo © Pete Eeles

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
1829Black HairstreakCurtis (1840)
1832Plumb HairstreakRennie (1832)
1852Dark HairstreakWood (1852)

Conservation Status

The status of the Black Hairstreak is considered stable, although the future of this fragile butterfly is dependent on appropriate protection and habitat management.

UK BAP StatusOccurrence Change
1976-2014 (%)
Abundance Change
1976-2014 (%)
Occurrence Change
2005-2014 (%)
Abundance Change
2005-2014 (%)
Species of Conservation Concern
Large Decrease-61
Large Decrease-54
Decrease-11
Large Decrease-87

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

Black Hairstreak colonies are typically located in small woods or nearby hedgerows, where Blackthorn, the larval foodplant grows. Wild Plum is also used occasionally. Sites are located in sheltered but sunny positions and typically have a southerly aspect to them.

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 butterfly has an extremely short flight period, being seen in the last 2 weeks of June and the first week of July. There is a single generation each year.

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

The adults spend much of their time resting high up on Maple, Ash or the larval foodplant, Blackthorn, crawling over leaves and twigs, in search of aphid honeydew from which they feed - making it extremely frustrating to get a sighting of this species. However, they will come down to feed on various nectar sources, Privet and Bramble flowers being particular favourites.

When active, the butterflies are extremely difficult to follow in flight - a characteristic of all hairstreaks. To make matters worse, the Black Hairstreak is often found in the company of both White-letter and Purple Hairstreaks and distinguishing these three species in flight is almost impossible. The butterfly always settles with wings closed and regulates its temperature by positioning its wings at an appropriate angle to the sun.

When engaged in courtship, male and female whirl around each other in a tireless dance which lasts for several minutes, ultimately resulting in the pair mating.

Adults feed primarily on Honeydew / Sap. Bramble (Rubus fruticosus), Buttercups (Ranunculus spp.), Hogweed / Angelica (Umbelliferae) and Privet (Ligustrum vulgare) are also used.

Satyrium pruni

Black Hairstreak, male and female, 30/05/2014, reared

Photo © Pauline
30-May-2014

Black Hairstreak female - M40 Compensation Area, 13-June-2014

Photo © Neil Hulme
13-Jun-2014

Black Hairstreak - imago - Thatcham - 15-Jun-10 (2) {REARED}

Photo © Pete Eeles
15-Jun-2010

Black Hairstreak - imago - Thatcham - 24-Jun-13 (16) [REARED]

Photo © Pete Eeles
24-Jun-2013

Black Hairstreak - Monks Wood, Cambridgeshire 14-June-2010

Photo © Neil Hulme
14-Jun-2010

Black Hairstreak - imago - Thatcham - 25-May-08 (3) {REARED}

Photo © Pete Eeles
25-May-2008

Black Hairstreak Female - Monks Wood, Cambs - June 2014

Photo © PhiliB

Black Hairstreak female - Whitecross Green Wood, Oxfordshire 20-June-07

Photo © Vince Massimo
20-Jun-2007

Black Hairstreak female - Glapthorn_09.15hrs_21/06/16

Photo © Kip
21-Jun-2016

Black Hairstreak - female - Thatcham - 30-Jun-13 (3) [REARED]

Photo © Pete Eeles
30-Jun-2013

Black Hairstreak - imago - Thatcham - 24-Jun-13 (7) [REARED]

Photo © Pete Eeles
24-Jun-2013

Black Hairstreak Female, Monks Wood, 25th June 2016

Photo © PhiliB

Black Hairstreak, 19/05/2014, Liphook reared

Photo © Pauline
19-May-2014

Black Hairstreak - male - Thatcham - 30-Jun-13 (2) [REARED]

Photo © Pete Eeles
30-Jun-2013

Black Hairstreak - Monks Wood, Cambridgeshire 14-June-2010

Photo © Neil Hulme
14-Jun-2010

Black Hairstreak - imago - Thatcham - 17-Jun-13 (1) [REARED]

Photo © Pete Eeles
17-Jun-2013

Black Hairstreak - Monks Wood - June 2009

Photo © Rosalyn
20-Jun-2009

Black Hairstreak - imago - Thatcham - 25-May-08 (1) {REARED}

Photo © Pete Eeles
25-May-2008

Black Hairstreak emerging from pupa,19/05/2014, reared

Photo © Pauline
19-May-2014

Black Hairstreak Female, Monks Wood, 25th June 2016

Photo © PhiliB

Photo Album (39 photos) ...


Ovum

Eggs are laid singly in the forks of small twigs of the foodplant, usually on a rough patch. The egg is blue-green when first laid, but gradually turns dark brown, ultimately becoming a pale grey with the onset of winter and often becomes discoloured due to algae which have formed on it. The larva is fully-formed within the egg as it passes the winter.

"The eggs are deposited singly at the base of the forks of the smaller branches and exactly resemble small brown buds. On June 23rd, 1904, two females were placed on a small plum tree, and during the following seven days a few eggs were laid on the smaller branches. This species passes the winter in the egg state, which lasts for about nine months. The egg is of a compressed spherical form, 0.80 mm. in width and 0.40 mm. high. The micropyle is sunken and finely pitted. The entire surface is covered with irregular raised reticulations, forming a cellular pattern surrounding the micropyle, increasing in size over the rest of the surface into a network pattern, chiefly in the form of hexagons; at the juncture of each mesh is a raised point with a cleft knobbed apex. The spaces between the meshes are granular. The ground colour is pale buff, the reticulations rust-brown and the points dark brown. During the winter it gradually becomes paler in colour, being in midwinter a light greyish-ochreous and the points black at the extremities, appearing to the naked eye of a general light grey-brown. They then remain unchanged until hatching about the end of March, being nine months in the egg state." - Frohawk (1924)

Black Hairstreak - ovum - Thatcham - 12-Mar-10 (2) {REARED}

Photo © Pete Eeles
12-Mar-2010

Black Hairstreak - ovum - Thatcham - 12-Mar-10 (1) {REARED}

Photo © Pete Eeles
12-Mar-2010

Black Hairstreak - ovum - Thatcham - 10-Mar-13 (1) [REARED]

Photo © Pete Eeles

Black Hairstreak - ovum - Thatcham - 10-Mar-13 (2) [REARED]

Photo © Pete Eeles

Black Hairstreak - ovum - Thatcham - 10-Oct-15 [REARED]-4

Photo © Pete Eeles
10-Oct-2015

Black Hairstreak - ovum - Thatcham - 10-Oct-15 [REARED]-5

Photo © Pete Eeles
10-Oct-2015

Black Hairstreak - ovum - Thatcham - 10-Oct-15 [REARED]-6

Photo © Pete Eeles
10-Oct-2015

Black Hairstreak - ovum - Thatcham - 10-Oct-15 [REARED]

Photo © Pete Eeles
10-Oct-2015

Photo Album (8 photos) ...


Larva

The egg hatches in spring, without eating the eggshell, the newly-emerged larva sits on a flower bud which it proceeds to eat, making good use of its extensible neck. More-mature larvae rest on the leaves of the foodplant, eating the tenderest leaves.

Although the appearance of the larva changes as it matures, it is always well-camouflaged and always matching the flower buds or leaves on which it feeds. The larva feeds during the day and has 4 instars in total.

The primary larval foodplant is Blackthorn (Prunus spinosa). Wild Plum (Prunus domestica) is also used.

Black Hairstreak, 2nd instar, 30/04/2014 (Reared)

Photo © Pauline
30-Apr-2014

Black hairstreaks, 1st and 2nd instar, 30/04/2014 (Reared)

Photo © Pauline
30-Apr-2014

Photo Album (2 photos) ...


1st Instar

"On March 26th and 27th, 1905, the eggs hatched. The larva eats away the central portion of the crown of the egg, leaving a comparatively large hole, and emerges. Directly after emergence it measures 1.3 mm. long, of the usual onisciform shape. The third to ninth segments are humped dorsally, the first and last segments somewhat flattened, and each with a shining black disc. The head is also shining black and bears a few tiny bristles. There is a central dorsal furrow and a row of hairs running along each side, composed of two hairs on each segment, both curving backwards, the anterior one being twice the length of the other; they have black, shining, pedestal-like bases; below these is a minute sub-dorsal hair, almost touching a double, black, shining wart. The spiracles are large and shining black. Along the lateral sub-spiracular region on each segment is a cluster of four hairs of different lengths, each having a shining black, bulbous base, and shorter hairs are scattered over the ventral surface and claspers. The whole colouring is lilac-brown, becoming ochreous on the ventral surface. The entire surface is granular and covered with minute shining points. Just previous to the first moult it measures only 1.8 mm. long. During the first stage it exactly resembles the outer sheath of the bud of blackthorn (P. communis) on which the larva were placed as soon as they hatched, which remains attached to the base of the young shoot; these are yellow with rust-brown tips. The larva is of similar colouration, having the fifth, sixth and seventh segments light ochreous-yellow, the remaining segments at each end reddish-brown." - Frohawk (1924)

Black Hairstreak - larva - Unknown location - Unknown date (2) [REARED] [Reg Fry]

Photo © Reg Fry

Black Hairstreak - 1st instar larva - Thatcham - 15-Apr-16 [REARED]-2

Photo © Pete Eeles
15-Apr-2016

Black Hairstreak - 1st instar larva - Thatcham - 15-Apr-16 [REARED]

Photo © Pete Eeles
15-Apr-2016

Photo Album (3 photos) ...


2nd Instar

"The first moult occurred on April 13th, the first stage occupying eighteen days. After first moult, twenty-five days old, it measures 3.2 mm. long. The first and last segments are rather compressed. The back is humped and considerably elevated, with a central dorsal longitudinal furrow. Each hump has a series of sharply pointed, serrated bristles with pedestal bases; these form a longitudinal fringe along each side of the furrow. The sides are concave with a prominent lateral ridge, also furnished with a fringe of bristles similar to those on the dorsal surface, and immediately below is another series of long, fine, simple, cream-coloured hairs; both series project laterally; the bristles are ochreous with blackish tips. Scattered over the body are numerous short bristles and lenticles. The head is pale ochreous and black. The fifth, sixth and seventh segments are varied in colouring, with yellowish pale green and pink; the remaining segments are purplish-rose. The ventral surface, claspers and legs are greenish-white." - Frohawk (1924)

Black Hairstreak - 2nd instar TBC - Thatcham - 28-May-16 [Thatcham]

Photo © Pete Eeles
28-May-2016

Photo Album (1 photos) ...


3rd Instar

"Seven days after the second moult it measures 6.35 mm. long. In shape it is similar to the previous stage. The head is shining black and while at rest is concealed under the projecting flattened anterior segment. The dorsal area, excepting the fifth, sixth and seventh segments, is a deep rose colour, and a beautiful rich rose tint exists on the lateral ridge of the second, third, fourth and fifth segments, becoming white on the sixth, seventh and eighth segments and rich rose on the last four segments, extending round the anal extremity. The central third of the body is pale yellowish-green, with darker green oblique stripes. On the inner dorsal edge of the fifth, sixth and seventh segments is a deep rose crescentic mark externally edged with whitish. The spiracles are pale amber-brown. The whole surface is densely sprinkled with minute spines. Along the dorsal and lateral ridges are clusters of much longer spines on each segment, excepting the eleventh. The whole of the ventral surface is of a greenish-pearly-white. It feeds deeply into the tender shoots of its food plant." - Frohawk (1924)

Black Hairstreak - larva - Thatcham - 22-Apr-08 (2) {REARED}

Photo © Pete Eeles
22-Apr-2008

Black Hairstreak - larva - Thatcham - 22-Apr-08 (3) {REARED}

Photo © Pete Eeles
22-Apr-2008

Black Hairstreak - larva - Thatcham - 22-Apr-08 (6) {REARED}

Photo © Pete Eeles
22-Apr-2008

Black Hairstreak - larva - Thatcham - 22-Apr-08 (7) {REARED}

Photo © Pete Eeles
22-Apr-2008

Black Hairstreak - larva - Thatcham - 13-May-13 (1) [REARED]

Photo © Pete Eeles

Black Hairstreak - larva - Thatcham - 18-May-13 (8) [REARED]

Photo © Pete Eeles

Photo Album (6 photos) ...


4th Instar

"The third and last moult takes place during the last week of May. After third moult, fully grown, it measures when crawling 15.9 mm. long. The head is pearly-white with slight greenish reflections marked with pale olive in front. The mouth parts are red-brown and white; eye spots black. The first segment is compressed and rounded, completely overlapping the head, and indented in the centre, where there is a glazed, whitish disc. The body is much elevated dorsally. The second, third and fourth segments are not humped, but merely sunken in the centre, forming very slight dorsal ridges. The fifth, sixth, seventh, eighth and ninth segments inclusive are strongly humped, each segment rising to a point on the dorsal ridge, leaving a deep central furrow; these points have each a sub-marginal, crescentic, rich, deep purple-rose mark on the inner side, and externally outlined with white on the fifth, sixth and seventh segments. The anal segment has a longitudinal dorsal mark of the same rose colour, and a paler rose tint blended round the lateral edge. The ground colour is a clear green, with four oblique pale yellow-green stripes and a longitudinal lateral line of the same colour. The ventral surface is whitish-green, including the legs and claspers. The whole surface above the lateral ridge is densely sprinkled with minute amber-brown spines, each with a fluted pedestal base. They are sparsely serrated and sharply pointed, and are longest on the dorsal area. On the tenth segment is a much longer pair, each in the middle of the dorsal ridge; these are duplicated on the eleventh segment by a much shorter pair. The spiracles are prominent, of a bright amber-brown. On each segment are numerous tiny greenish, glassy discs. The larva in this stage continues feeding almost unceasingly for several hours' duration. The author could not detect it stopping. The last stage occupies about ten days." - Frohawk (1924)

Black Hairstreak - larva - Thatcham - 09-May-08 (1) {REARED}

Photo © Pete Eeles
09-May-2008

Black Hairstreak - larva - Thatcham - 20-May-10 (1) {REARED}

Photo © Pete Eeles
20-May-2010

Black Hairstreak - larva - Thatcham - 20-May-10 (2) {REARED}

Photo © Pete Eeles
20-May-2010

Black Hairstreak - larva - Thatcham - 20-May-10 (3) {REARED}

Photo © Pete Eeles
20-May-2010

Black Hairstreak - larva - Thatcham - 20-May-10 (4) {REARED}

Photo © Pete Eeles
20-May-2010

Black Hairstreak - larva - Thatcham - 20-May-10 (5) {REARED}

Photo © Pete Eeles
20-May-2010

Black Hairstreak - larva - Thatcham - 17-Jun-13 (1) [REARED]

Photo © Pete Eeles
17-Jun-2013

Photo Album (7 photos) ...


Pupa

The pupa is superbly camouflaged as a bird dropping and is quite visible to the trained eye, attached to the upper surface of a leaf or twig. The pupal stage lasts around 3 weeks.

"One pupated on June 7th. The pupa is short, stout and humped. It measures 9.5 mm. long and 4.8 mm. in diameter across the third abdominal segment. Dorsal view: Head slightly notched in front, angular at base of wings, concave at the waist; abdomen swollen at the middle and abruptly attenuated to the anal segment. Lateral view: Head pointed in front; thorax swollen and rounded, sunken at the waist; abdomen suddenly rising to third segment, where it is strongly humped, it then curves to the anal segment; each segment has a sub-dorsal point, decreasing in size from the third segment; between these and the spiracles are two punctures on each segment; the under surface forms a straight line. Colour: Directly after pupation it is pale greenish, with paler thoracic markings; it gradually darkens, and in about forty-eight hours assumes its normal colouring, which is as follows: The ground colour of the dorsal surface is a clear brown-black, having a rather varnished appearance, becoming ochreous-brown by the spiracles and over the wings; it is variegated with white on the pro-thorax, hind portion of meso-thorax and whole of meta-thorax, also each side of the first abdominal segment, and speckled with white on the remaining segments bordering the wings; the spiracles are prominent, black and shining. The whole of the dorsal surface is sprinkled with tiny amber-coloured hairs. The wings and ventral surface, excepting the abdomen, are smooth. It is attached to the stem or leaf of its food plant by a silken cincture round the waist, and by the cremastral hooks to a silken pad. In general form and especially in colouring it exactly resembles a bird's excrement, which it undoubtedly mimics. Occasionally the larvae leave the blackthorns and pupate on the vegetation growing near the bases of the bushes. The pupal state occupies about eighteen days. The one described emerged on June 25th, which is about the normal time for the appearance of the butterfly." - Frohawk (1924)

Black Hairstreak - pupa - Thatcham - 09-May-08 (6) {REARED}

Photo © Pete Eeles
09-May-2008

Black Hairstreak - pupa - Thatcham - 09-May-08 (7) {REARED}

Photo © Pete Eeles
09-May-2008

Black Hairstreak - pupa - Thatcham - 13-May-08 (1) {REARED}

Photo © Pete Eeles
13-May-2008

Black Hairstreak - pupa - Thatcham - 13-May-08 (4) {REARED}

Photo © Pete Eeles
13-May-2008

Black Hairstreak - pupa - Brampton Wood, 12th June 2010 (aka Trev)

Photo © NickB
12-Jun-2010

Black Hairstreak - pupa - Thatcham - 31-May-10 (1) {REARED}

Photo © Pete Eeles
31-May-2010

Black Hairstreak - pupa - Thatcham - 31-May-10 (2) {REARED}

Photo © Pete Eeles
31-May-2010

Black Hairstreak - pupa - Thatcham - 31-May-10 (3) {REARED}

Photo © Pete Eeles
31-May-2010

Black Hairstreak - pupa - Thatcham - 31-May-10 (4) {REARED}

Photo © Pete Eeles
31-May-2010

Black Hairstreak - pupa - Thatcham - 17-Jun-13 (1) [REARED]

Photo © Pete Eeles
17-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (1) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (2) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (3) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (4) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (5) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (6) [REARED]

Photo © Pete Eeles
21-Jun-2013

Black Hairstreak - pupa - Thatcham - 21-Jun-13 (7) [REARED]

Photo © Pete Eeles
21-Jun-2013

Photo Album (17 photos) ...


Aberrations

Description to be completed.

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

Similar Species

White-letter Hairstreak

Both Black Hairstreak and White-letter Hairstreak are very local species, but do fly together on rare occasions. There are two features that distinguish these species. The first is that the Black Hairstreak has a row of distinctive black dots running along the inside of the orange band on the underside of the hindwing, that is absent in the White-letter Hairstreak. The second is that the White-letter Hairstreak has a more pronounced white line on its hindwing, forming a letter "W" from which the White-letter Hairstreak gets its name. This line is less prominent in the Black Hairstreak.


Black Hairstreak (left) and White-letter Hairstreak (right)

Videos


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The following links provide additional information on this butterfly.

References

The species description provided here references the following publications:

ReferenceDetails
Butler (1869) Butler, A.G. (1869) Catalogue of diurnal Lepidoptera described by Fabricius in the collection of the British museum.
Curtis (1840) Curtis, J. (1840) British Entomology [1823-1840].
Doubleday (1847) Doubleday, E. (1847) List of the Specimens of Lepidopterous Insects in the Collection of the British Museum.
Frohawk (1924) Frohawk, F.W. (1924) The Natural History of British Butterflies.
Leach (1815) Leach (1815) In Brewster: The Edinburgh Encyclopaedia.
Linnaeus (1758) Linnaeus, C. (1758) Systema Naturae. Edition 10.
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.
Scudder (1876) Scudder, S.H. (1876) Bulletin of the Buffalo Society of Natural Sciences.
Wood (1852) Wood, W. (1852) Index Entomologicus; or, A Complete Illustrated Catalogue, Consisting of 1944 Figures, of the Lepidopterous Insects of Great Britain. Edition 2.