White-letter Hairstreak

Satyrium w-album

About

White-letter hairstreaks are small butterflies that breed on elm trees. These small butterflies prefer the tops of the trees so are hard to spot and easily missed.

How to identify

Key identification features of this small brown butterfly are the small hairs located at the base of the wings and the white W-shaped line on the underside of the wing, from which it gains its name.

Where to find it

Mostly in England and Wales, with a few isolated records in Scotland.

Habitats

When to find it

  • June
  • July
  • August

How can people help

White-letter hairstreaks are estimated to have suffered a 99% population decline over the last 25 years in the UK. The eggs of white-letter hairstreaks are laid on elm trees, which the caterpillars feed on in spring and the decline may in part be due to the loss of their larval food plant due to Dutch elm disease. If you have hedges with elm trees where white-letter hairstreaks may be present, encourage the presence of food plants such as bramble or hogweed. This species may also be under-recorded so please report any sightings to your county Wildlife Trust or biological record centre.

Species information

Common name
White-letter Hairstreak
Latin name
Satyrium w-album
Category
Invertebrates
Butterflies and moths
Statistics
25-35mm wingspan