Belongs to: blues and hairstreaks
Compare with: gatekeeper
Brown hairstreak Thecla betulae
Vulnerable
Best time to see: late Jul to end Sep
Key facts
An elusive golden hairstreak butterfly that spends most of its time feeding or congregating in the treetops
Habitat: around large ash trees or laying eggs nearby on blackthorn or related species, such as wild cherry
Restricted to southern England and west Wales
Recognition
Golden underwings crossed by thin white lines and with a distinct tail; 38–40mm; usually perch with closed wings
Congregate around large ash trees in high summer, drinking honeydew from aphids and looking for mates
Males rarely leave the treetops, but females disperse to lay eggs
Lifecycle
After mating, females descend to lay eggs singly low down on blackthorn or other shrubs
Caterpillars are triangular, pale green with yellow stripes
They pupate in July, emerging as adults from late July onwards
© Charles J Sharp