Brown Hairstreak

• Latin name: Thecla betulae
• Family group: Hairstreaks
• Countries: England, Wales, Ireland
• Size: Small, Medium

Resident

Range declining.

The Brown Hairstreak is an elusive butterfly that spends most of its life either high in the tree canopy or hidden amongst hedgerows. It is worth looking up at prominent Ash trees along wood edges to see if small clusters of adults may be flitting around a 'master' tree where they congregate to mate and feed on aphid honeydew. Alternatively, adults sometimes feed lower down on flowers such as Hemp-agrimony, Common Fleabane, and Bramble. The females are most frequently seen as they disperse widely along hedgerows where they lay conspicuous white eggs on young Blackthorn.

The butterfly is locally distributed in southern Britain and mid-west Ireland and has undergone a substantial decline due to hedgerow removal and annual flailing, which removes eggs.

Conservation status

• UK Biodiversity Action Plan: Priority Species
• Butterfly Conservation priority: high
• European threat status: not threatened
• Protected in Great Britain for sale only

European/world range

Widely distributed across central Europe from northern Spain to southern Sweden, and east through Asia to Korea. Declining in many European countries.

Foodplants

The butterfly breeds on young growth of Blackthorn (Prunus spinosa) and occasionally other Prunus species such as Bullace (P. domestica).

Habitat

Hedges, scrub, and wood edges are used where Blackthorn is abundant and not too intensively managed. The butterfly typically breeds over wide areas of countryside with extensive networks of hedges and woodland, often on heavy clay soils in low-lying land. In contrast, most Irish colonies are on lighter soils over limestone bedrock.