Brown Hairstreak

Thecla betulae (THECK-luh bet-YOU-lee)

Brown Hairstreak, Steyning Coombe, Sussex 19-Aug-2015
Photo © Neil Hulme
 

Wingspan
Male: 36 - 41mm
Female: 39 - 45mm

Checklist Number
61.003

Family:LycaenidaeLeach, 1815
Subfamily:TheclinaeButler, 1869
Tribe:ThecliniSwainson, 1831
Genus:TheclaFabricius, 1807
Subgenus:  
Species:betulae(Linnaeus, 1758)

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Introduction

This is the largest hairstreak found in the British Isles. It is a local species that lives in self-contained colonies that breed in the same area year after year. This species can also prove elusive, since it spends much of its time resting and basking high up in tall shrubs and trees. The female is particularly beautiful, with forewings that contain large orange patches, and was once considered to be a separate species known as the "Golden Hairstreak". This species is found in the southern half of England and Wales, and also around the Burren in Ireland. In England its strongholds are in West Sussex, Surrey, Oxfordshire, Buckinghamshire, North Devon and South Devon. Strongholds in Wales are in Cardiganshire and Carmarthenshire. In Ireland it is primarily found in the Burren limestones of Clare and South-east Galway. The northernmost sites are found in North Lincolnshire.

Thecla betulae

This species was first defined in Linnaeus (1758) as shown here (type locality: Sweden).

Male Brown Hairstreak, Shipton Bellinger, 06/08/2013

Male
Photo © Pauline

Brown Hairstreak - Male - Shipton Bellinger - 09.08.13

Male Underside
Photo © PhiliB

Brown Hairstreak - Knepp Estate, Sussex 8-Aug-2013

Female
Photo © Neil Hulme

Brown Hairstreak female - Knepp Estate, Sussex 3-Aug-2013

Female Underside
Photo © Neil Hulme

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Conservation Status

The long-term trend for this species shows a severe decline and it is therefore a priority species for conservation efforts. Unsympathetic farming practices that involve the flailing of hedgerows containing overwintering eggs are considered to be one factor in this demise.

UK BAP StatusDistribution Trend (%)Population Trend (%)
Priority Species
Click here to access the Biodiversity Action Plan (BAP) for this species.
Stable+1
Decrease-40

The table above shows the distribution and population trends of species regularly found in the British Isles. The distribution trend represents a comparison between data for the periods 1995-1999 and 2005-2009. The information provided is taken from the Butterfly Conservation report The State of the UK's Butterflies 2011. The UK BAP status is taken from the UK Biodiversity Action Plan (UK BAP) (2007 review).

Habitat

This species lives in habitats where Blackthorn, the primary larval foodplant, is abundant, such as hedgerows and woodland.

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. Alternatively, select one of the sites listed below.

Sites
Alner's Gorse, Anstey's Cove, Asham Meads, Bernwood Forest, Bernwood Meadows, Bookham Common, Boston, Carymoor Environmental Centre, Chambers Farm Wood, Cissbury Ring, Collard Hill, Dromore Wood, East Poldens Reserves, Grafton Wood, Green Down Nature Reserve, Hatton Meadows, Horley, Ifield, Langford Heathfield, Levin Down, Little Breach, Lough Bunny, Lydlinch Common, Mansmead wood, Mount Fancy Reserve, Noar Hill, Orley Common, Otmoor RSPB Reserve, Piddington Wood, Pulborough Brooks (RSPB), Rushbeds Wood, Shipton Bellinger, Somerford Common, Steyning Downs, Steyning Rifle Range, Stoke Common Meadows, Thurlbear Quarrylands, Warnham LNR, Welsh Wildlife Centre, West Williamston Salt Marshes, Whitecross Green Wood, Witch Lodge Fields

Life Cycle

There is one generation each year. This is one of the latest species to emerge in the British Isles, with adults first seen on the wing in late July or early 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

Adults emerge in the morning and males generally appear a few days before females. This is a warmth-loving butterfly, and is rarely seen on overcast days. On sunny days the adults will rest with wings open, absorbing the sun's rays on their dark brown wings which gradually close as they warm up. In flight, the adults are easily mistaken for the Gatekeeper, which flies at the same time.

The males are the more-elusive of the two sexes, congregating high on ash "master trees" that are positioned around the breeding area, where they feed on honeydew. They occasionally come down to feed on various nectar sources, such as Hemp Agrimony, probably when honeydew is scarce. When they do come down, however, they can be remarkably tame and easy to observe. Mating occurs without any discernable courtship, typically high in a tree.

Females also spend their time on the master trees until the eggs have matured and they are ready to lay. They then disperse and alternate between basking in the warm sunshine, feeding from nectar sources, and egg-laying. Egg-laying sites are typically in sheltered areas at the edges of woodland or hedgerows where younger growth that is south-facing is favoured. The female will crawl among the branches of the foodplant, feeling the branches for appropriate sites, when egg-laying.

Adults feed primarily on Honeydew / Sap. Bramble (Rubus fruticosus), Devil's-bit Scabious (Succisa pratensis), Hemp Agrimony (Eupatorium cannabinum), Hogweed / Angelica (Umbelliferae), Ragwort (Senecio jacobaea) and Thistles (Cirsium spp. and Carduus spp.) are also used.

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Ovum

The sea urchin-shaped eggs are laid singly on the bark of the foodplant, typically at a fork in a branch that is on one- or two-year old growth that is in a sheltered area exposed to the sun. Eggs are laid at low density over large areas, but 2 or 3 eggs are found together on occasion. The larva partially develops within the egg before entering hibernation for the winter. Overwintering eggs are particularly vulnerable to hedge-trimming since they are laid on the youngest growth of the foodplant.

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

Photo © Pete Eeles

Brown Hairstreak - ovum - Thatcham - 10-Mar-13 (3) [REARED]

Photo © Pete Eeles

Brown Hairstreak egg [Gillian Thompson]

Photo © Gillian Thompson
04-Sep-2011

Brown Hairstreak Ovipositing

Photo © Pete Withers

Photo Album ...


Larva

The larva emerges from the egg in spring by cutting a hole in the top of the egg and immediately enters a developing bud. The eggshell is not eaten and may be found some time after the larva has emerged. After the first moult, the larva will rest by day on a silk pad situated on the underside of a leaf, feeding away from its resting place at night, and returning to rest as dawn approaches. The bright green larva is extremely well-camouflaged, blending perfectly with the leaf on which it sits. The fully-fed larva leaves the foodplant prior to pupation, changing colour to a dull purple to maintain the excellent camouflage as it rummages around in leaf litter. There are 3 moults in total.

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

Brown Hairstreak - larva - Thatcham - 24-Jun-13 (1) [REARED]

Photo © Pete Eeles
24-Jun-2013

Brown Hairstreak Larva (6 hours before pupation) (Reared) Caterham, Surrey 13-June-11

Photo © Vince Massimo
13-Jun-2011

Brown Hairstreak larva pupating - Crawley, Sussex 28-June-2015

Photo © Vince Massimo
28-Jun-2015

Brown Hairstreak - larva - Thatcham - 04-Jul-09 (2) {REARED}

Photo © Pete Eeles
04-Jul-2009

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Pupa

The pupa is formed in a crevice in the ground, amongst the leaf litter or at the base of a plant. It has been known for a pupa to be buried by ants, which find it highly attractive, in a loose cell of dry earth. It is believed that mice and shrews are responsible for eating large numbers of pupae in the wild. This stage lasts around 4 weeks.

Brown Hairstreak pupa (freshly emerged) - Crawley, Sussex 28-June-2015

Photo © Vince Massimo
28-Jun-2015

Brown Hairstreak Pupa (freshly emerged) (Reared) Caterham, Surrey 13-June-11

Photo © Vince Massimo
13-Jun-2011

(Reared) Attached shed skin created imaginary 'facial features' with interesting hairstyle

Photo © tomdunbar
25-Jun-2006

Brown Hairstreak Pupa (Reared) Caterham, Surrey 2-July-11

Photo © Vince Massimo
02-Jul-2011

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Aberrations

Description to be completed.

This section shows those aberrations for which there is a corresponding image. Click here to see the descriptions of other aberrations for this species.

ab. lata (Tutt.Brit.Lep.1907.9.p.279.)

Female. The orange patch at the end of the cell broad but not crossed by black nervures.

Brown Hairstreak - imago - Thatcham - 23-Jul-06 (0459) [REARED]

Photo © Pete Eeles
23-Jul-2006

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ab. spinosae (Gerhard.Mon.Beitr.Schmett.1853.pl.3.f.2.)

Male. Brown with an orange patch at the end of the discoidal cell and two smaller interneural patches beneath.

Brown Hairstreak - imago - Thatcham - 31-Jul-09 (1) {REARED}

Photo © Pete Eeles
31-Jul-2009

Brown Hairstreak - imago - Thatcham - 31-Jul-09 (2) {REARED}

Photo © Pete Eeles
31-Jul-2009

Brown Hairstreak - imago - Thatcham - 31-Jul-09 (3) {REARED}

Photo © Pete Eeles
31-Jul-2009

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ab. uncilinea (Tutt.Brit.Lep.1907.9.p.280.)

Underside. The inner white line on the hindwings is curved upwards at the bottom in the form of a hook.

Brown Hairstreak ab. uncilinea - Whitecross Green Wood

Photo © Trev Sawyer

Brown Hairstreak (f) ab unclilinea 100dpi Whitecross Green Wood 080729 9161 [David Newland]

Photo © David Newland
29-Jul-2008

Brown Hairstreak female (ab. uncilinea) - Steyning, East Sussex 12-Aug-2015

Photo © Neil Hulme
12-Aug-2015

Photo Album ...


Similar Species

No similar species found.

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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.
Fabricius (1807) Fabricius, J.C. (1807) Magazin für Insektenkunde, herausgegeben von Karl Illiger.
Leach (1815) Leach (1815) In Brewster: The Edinburgh Encyclopaedia.
Linnaeus (1758) Linnaeus, C. (1758) Systema Naturae. Edition 10.
Swainson (1831) Swainson, W. (1831) Zoological illustrations, or, Original figures and descriptions of new, rare, or interesting animals, selected chiefly from the classes of ornithology, entomology, and conchology, and arranged according to their apparent affinities.