White-letter Hairstreak
Satyrium w-album
Conservation status data sourced from the IUCN Red List of Threatened Species.
49
Countries
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/White-letter_hairstreak
Taxonomy & Classification
Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Lepidoptera
Family
Lycaenidae
Genus
Satyrium
White-letter Hairstreak belongs to the family Lycaenidae, order Lepidoptera, within the Insecta class.
Species Profile
Species profile data sourced from the IUCN Red List of Threatened Species.
The White-letter Hairstreak faces severe population declines primarily due to Dutch elm disease, which has devastated its primary host plant, elm trees, across much of its range. Habitat fragmentation and loss of mature elm trees through urban development and agricultural intensification have further reduced available breeding sites. Climate change may also be affecting the synchronization between butterfly emergence and elm leaf development.
Key Facts
Habitat & Distribution
Mature elm woodlands, hedgerows with large elm trees, and woodland edges where elm species (particularly English elm, wych elm, and field elm) form the canopy. The species requires established elm trees for egg-laying and larval development, typically in areas with some shelter and connectivity to other elm populations.
Threats
IUCN Red List: Critically Endangered
The White-letter Hairstreak faces severe population declines primarily due to Dutch elm disease, which has devastated its primary host plant, elm trees, across much of its range. Habitat fragmentation and loss of mature elm trees through urban development and agricultural intensification have further reduced available breeding sites. Climate change may also be affecting the synchronization between butterfly emergence and elm leaf development.
Dutch elm disease destroying host plants
Habitat fragmentation and urbanization
Loss of mature elm trees
Agricultural intensification
Climate change affecting phenology
Found in 49 Countries
National vs Global Threat Status
How this species is assessed at the national level compared to its IUCN global status (CR).
| Country | National Status | Global Status | Comparison |
|---|---|---|---|
| EU | LCLeast Concern | CRCritically Endangered | Lower local risk |
| EU | LCLeast Concern | CRCritically Endangered | Lower local risk |
National Red List data sourced from the National Red List Project (nationalredlist.org, ZSL) and country-specific Red List authorities.
Community Sightings
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Sources & Attribution
How to Cite
IUCN: IUCN (2025). The IUCN Red List of Threatened Species. Version 2025-1. Available at: https://www.iucnredlist.org. doi:10.2305/IUCN.UK.2025-1.RLTS
GBIF: GBIF.org (2025). GBIF Home Page. Available at: https://www.gbif.org
National Red Lists: ZSL (2025). National Red List. Zoological Society of London. Available at: https://www.nationalredlist.org
This page: SpeciesRadar (2025). White-letter Hairstreak (Satyrium w-album). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/white-letter-hairstreak