Where to see
Habitat: Hedges and woodland edges which extend across a wide area.
Caterpillar foodplants: Mainly blackthorn, occasionally other prunus species.
Best places: The only place you are fairly certain to see the Brown Hairstreak in Dorset (at the right time) is at our Alners Gorse Butterfly Reserve. They have been reported at Lydlinch, also in North Dorset.
When to see
Mainly July and into August, possibly September
Sightings by month (last 5 years)*:
Sightings this year*:
This butterfly is not seen in large numbers, as it tends to lay its eggs across a wide area. It is declining across the UK and only just hangs on in Dorset, where our Alners Gorse Reserve is being especially managed for it. It is not easily seen as an adult butterfly, because the males spend almost all their time feeding and mating high up on the tallest trees in the colony known as ‘master trees’. However once they have mated females do come down to lay on blackthorn shrubs in August and September. Surveys are often undertaken by counting eggs in the winter, because they are easier to find than the adult butterflies.
The Brown Hairstreak tends to sit with its wings closed, but you will sometimes catch it with its wings open, soaking up the sun. All the Hairstreaks have small tails to the hind wings.
Male underwings are less bright than those of females, which can be so golden in colour that they were once thought to be a separate species, the Golden Fritillary.
Only females have a definite orange patch on their upperwings, the males being more brown with just a dash of duller orange. Females have longer tails, but this can be difficult to see in the wild.
Occasionally confused with the Gatekeeper, which can seem orange when the sun catches it flying high, but more often with the day-flying male Vapourer Moth, though this is smaller and very different close up.
The presence and abundance of the Brown Hairstreak is often assessed by searching for the eggs in winter.
*Note: The charts shown on this page are drawn only from casual sightings submitted to this website. Records from this website will be added to a lot more data collected throughout the year and used to compile the five-yearly Butterfly Atlases for Dorset and the UK.