Essex Emerald
Thetidia smaragdaria
The Essex emerald is a moth of the family Geometridae. The species was first described by Johan Christian Fabricius in 1787 as Phalaena smaragdaria.
49
Countries
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Essex_emerald
Taxonomy & Classification
Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Lepidoptera
Family
Geometridae
Genus
Thetidia
Essex Emerald belongs to the family Geometridae, order Lepidoptera, within the Insecta class.
Species Profile
The Essex emerald is a moth of the family Geometridae. The species was first described by Johan Christian Fabricius in 1787 as Phalaena smaragdaria. It is distributed throughout the Palearctic region with records from many European countries. The British subspecies Thetidia smaragdaria maritima was last seen in 1991 in Kent and is now presumed extinct. In 2004 the moth was first recorded from Sweden.
The Essex Emerald is critically threatened by habitat loss due to coastal development and sea level rise affecting its specialized saltmarsh habitat. The species has an extremely restricted range limited to a few sites in Essex, England, making it highly vulnerable to local extinctions from habitat degradation and climate change impacts.
Key Facts
Habitat & Distribution
Threats
IUCN Red List: Endangered
The Essex Emerald is critically threatened by habitat loss due to coastal development and sea level rise affecting its specialized saltmarsh habitat. The species has an extremely restricted range limited to a few sites in Essex, England, making it highly vulnerable to local extinctions from habitat degradation and climate change impacts.
Coastal development and urbanization
Saltmarsh habitat degradation
Sea level rise and coastal erosion
Climate change altering host plant distribution
Small population size and genetic bottlenecks
Found in 49 Countries
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
This page: SpeciesRadar (2025). Essex Emerald (Thetidia smaragdaria). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/essex-emerald