White-letter Hairstreak

Satyrium w-album (Knoch, 1782)



A small dark brown butterfly. Male and female are similar. The butterfly has one brood a year. It can be easily confused with members of the genius. On the hindwing underside, the postdiscal white line (hairstreak) has a distinct W shape in the anal area, along with a short tail. The orange submarginal band is bordered with a black line basally. Whereas S. acaciae tails is hardly noticeable, and S. ilicis has orange spots rather than a band, and without the distinct W-shape.

Habitat Requirements

An arboreal species, found in close association with elms.

Larval Foodplants

Wych Elm Ulmus glabra, Small-leaved Elm Ulmus minor


Another under recorded species because it spends most of its adult life in the canopies of the various Elms. Once encountered, it can regularily be seen at the same location year after year.

Anne Sordinas discovered a colony at Mon Repo, where the adult butterflies are reliably seen nectaring on umbellifers below their host Elms. Given that Elm is widely distributed throughout Corfu, its almost certain that the distribution of S. w-album is far greater than generally known.

*The information provided in the tables below is based on verified sightings of the White-letter Hairstreak submitted via this website since 1st January 2021.

First and Last Sightings

Year First Last/latest # Days
2023 15/05/2023 23/05/2023 8 days
2022 25/05/2022 12/06/2022 18 days
2021 12/05/2021 23/05/2021 11 days

Number of Observations

Year Number of observations
2023 38
2022 8
2021 22
Grand Total 68

Distribution Map

Distribution maps for this species are currently unavailable.

Flight Times for the White-letter Hairstreak (2023)

The chart below shows flight data by month for 2023 submitted online since 1st January 2023 to 28th May 2023.

Flight Times for the White-letter Hairstreak (All Data)

The chart below shows flight data by month based on all data submitted online since 1st January 2019 to 28th May 2023.


  • Vernacular/Common Name: White-letter Hairstreak
  • Family: Lycaenidae (Leach, 1815)
  • Sub-family: Theclinae (Swainson 1831)
  • Tribe: Eumaeini (Doubleday 1847)
  • Genus: Satyrium (Scudder, 1876)
  • Sub-genus: Satyrium (Scudder, 1876)
  • Species: w-album (Knoch, 1782)


For a list of references, please see our bibliography page.