A green butterfly with a small line of white streaks on the underside of its hindwing

Green Hairstreak. Photo: John Woodruff.

Our only green butterfly. The green is actually only on the underwings: the upperside is pale brown, but rarely seen. A small butterfly.

Where to see

Habitat: Found in a variety of habitats: calcareous grassland, woodland rides, moorland and rough scrubby grassland.

Caterpillar foodplants: The caterpillar foodplant depends on the habitat. In calcareous areas it will be the Common Rock-rose or Common Bird's-foot trefoil. On heathland, they use Gorse, Broom and Dyer's Greenweed. Other foodplants can include Bilberry, Dogwood, Buckthorn, Cross-leaved Heath and Bramble.

Best places: Widely distributed, but generally in small colonies, so it can be difficult to find. Try Upton Country Park, Bindon Hill (near Lulworth), Cashmoor Down or the Cerne Giant hillside.

Reported from the following locations last year*:

When to see

Mainly May and into June, sometimes a little earlier or later.

Sightings by month (last 5 years)*:

Sightings this year*:


Notes

Size: small.

The male and female look very similar. You may be able to differentiate them by their behaviour: the males may be seen having territorial battles with each other, after which the winner retires to his favourite perch on a prominent bush from 1-2 meters up, where he is easy to watch or photograph. The female is more often seen fluttering around bushes or plants where she searches to find good places to lay her eggs.

Both have brown uppersides and will therefore look brown in flight. When resting, their wings are always closed, so you only see the green undersides. These have a white dotted line on the hindwing, but this is very variable, to the point where it may be one white spot or nothing at all, while it can sometimes extend onto the forewing (see the photo at the top of the page). Some will have a brownish edge to the forewing where it disappears behind the forewing. All the Hairstreaks have small tails to the hind wings.

Some specimens (fresher ones?) will have a brown edge to the wing, and a small white fringe.

Photo gallery

Click thumbnails to view larger images.

*Please 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.