Brown hairstreak

Species of butterfly

The brown hairstreak (Thecla betulae) is a butterfly in the family Lycaenidae. The range includes most of the Palaearctic.

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

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.

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.

This butterfly species is protected in the UK via Schedule 5 of the Wildlife and Countryside Act of 1981.