Sussex Emerald (Thalera fimbrialis)
Key Details
| Taxonomic Groups: | Invertebrate > insect - moth > Moth |
| Red List Status: | (Not Relevant) [(not listed)(nr)] |
| D5 Status: | |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Thalera fimbrialis |
| UKSI Recommended Authority: | (Scopoli, 1763) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | (not listed) |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | GB Red List (Fox et al. 2019): EN; no long-term trend data available. Highly restricted distribution; until very recently restricted to coastal shingle in Kent. Bespoke monitoring (2002-2021) of the core population at Dungeness indicates a marked and ongoing decline. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | The core population requires ongoing rabbit control to maintain good coverage of the host plant Wild Carrot. Also requires bespoke status surveys and monitoring. |
| Question 3: | At a landscape scale, would the species benefit from untargeted habitat management to increase habitat mosaics, structural diversity, or particular successional stages? |
| Response: | Yes |
| Justification: | The moth is fairly mobile and will colonise new breeding habitat within dispersal range of source populations. Creation of early-mid successional habitat on the coast should benefit this species. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 6. Recovery solutions trialled |
| Recovery potential/expectation: | Medium-high |
| National Monitoring Resource: | Structured - sufficient |
| Species Comments: |
Key Actions
Key Action 1
Proposed Action: Within the last few years the moth has colonised at least two inland sites, one a coal spoil site and the other a chalk grassland reversion from arable. Undertake ecological research at these sites to determine habitat requirements, including larval host plant use, and whether this differs from coastal shingle sites. This will help inform habitat creation at additional inland sites.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 2 years
Scale of Implementation: ≤ 5 sites
High priority sites: 2 sites in Kent
Comments:
Key Action 2
Proposed Action: Colonisation of an arable reversion site at Barham Downs indicates that the moth can now breed inland and on newly-restored habitat. Monitor additional restoration sites for colonisation by the moth, with follow up work to determine host plants and precise habitats used (Action 1).
Action targets: 6. Recovery solutions trialled
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: ≤ 10 sites
High priority sites: Downland arable reversion areas in East Kent
Comments:
Key Action 3
Proposed Action: Continue to survey all existing sites annually to maintain up to date information on species status and habitat condition. Adult and/or larval surveys as appropriate. Also survey potential sites in East Kent, Sussex and Essex, and continue annual larval monitoring at key sites.
Action targets: 2. Biological status assessment exists
Action type: Status survey/review
Duration: >10 years
Scale of Implementation: National
High priority sites: Dungeness, Rye Harbour and other sites with recent records
Comments:
Acknowledgment:
Data used on this website are adapted from Threatened species recovery actions 2025 baseline (JP065): Technical report and spreadsheet user guide (Natural England, 2025). Available here.