|Female, underside, Otmoor, Oxfordshire, England|
- T. b. betulae Europe, northern Caucasus, Transcaucasia, Saur, Tarbagatai, Dzhungarsky Alatau, Siberia, Amur, Ussuri. Larva on Prunus spinosa (Caucasus), Crataegus sanguinea, (southern Altai, Saur)
- T. b. crassa Leech, 1894 southern Ussuri. Larva on Prunus padus, Prunus mandshurica
- T. b. ongodai Tutt, 1908 Altai
- T. b. coreana (Nire, 1919) Korea. Larva on Fabaceae
- T. b. elwesi Leech, 1890 western and central China
- T. b. yiliguozigounae Huang & Murayama, 1992 China
Appearance and behaviour
A little butterfly that is found along hedges, scrub, and wood edges but is often overlooked since it spends much of its time high in the tree canopy. Like the purple emperor this butterfly uses 'master trees', usually European ash (Fraxinus excelsior). Males and unmated females congregate at the tops of isolated trees. Once mated the female descends to lower levels to begin laying her eggs. Males rarely descend and both feed mainly on honeydew. Both sexes are dark brown on the upperside with orange tails. The female also has a bright orange band across both forewings. The undersides are similar in both sexes and are bright orange with two white streaks.
Life cycle and food plants
In Europe the female lays her eggs on blackthorn (Prunus spinosa) in late August which overwinter, hatching the following spring when the buds are breaking. It has been found that the best way to find breeding sites for this species is to look for the conspicuous white eggs in the winter. The larvae are extremely well camouflaged and feed only at night, remaining motionless during the day. Pupation takes place in leaf litter on the ground in late June or early July and are attractive to ants who will bury them in shallow cells.
- Asher, Jim, Martin Warren, Richard Fox, Paul Harding, Gaile Jeffcoate & Stephen Jeffcoate (Eds), 2001. The Millennium Atlas of Butterflies in Britain and Ireland. Oxford University Press.
- Thomas, J.A. & A.M. Emmet, 1990. Thecla betulae (Linnaeus). Pages 123–126 in A. Maitland Emmet, John Heath et al. (eds) The Butterflies of Great Britain and Ireland. The Moths and Butterflies of Great Britain and Ireland Vol. 7, Part 1 (Hesperiidae to Nymphalidae). Harley Books, Colchester, UK.
- Thecla betulae Linnaeus, 1758. Species account at Butterfly Conservation Armenia species account 
- Butterfly Conservation page for Brown Hairstreak
- UK Butterflies web-page for Brown Hairstreak—including numerous images of all stages
- Field notes from a research study
- Butterfly-guide.co.uk entry
- Image of female underside
- Brown Hairstreak (upperwing)
- Brown Hairstreak (underwing)
- Brown hairstreak in Armenia