Large Blue (Phengaris arion)
Key Details
| Taxonomic Groups: | Invertebrate > insect - butterfly > Butterfly |
| Red List Status: | Near Threatened (Not Relevant) [NT(nr)] |
| D5 Status: | Included in the baseline Red List Index for England (Wilkins, Wilson & Brown, 2022) |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | Maculinea arion |
| UKSI Recommended Name: | Phengaris arion |
| UKSI Recommended Authority: | (Linnaeus, 1758) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Fox & Dennis, 2021 |
| 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. 2022): NT. Statistically significant 1883% increase in abundance since 1983 and a 111% short-term (10 year 2010-2019) increase; distribution trend not possible to calculate (Fox et al. 2023) |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Well researched ecology, specific grazing requirements on limestone grassland to ensure abundance of foodplant and Myrmica sabuleti ant presence |
| 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: | No |
| Justification: | Has very specific requirements and targeted grazing management is required. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 7. Best approach adopted at appropriate scales |
| Recovery potential/expectation: | Medium-high |
| National Monitoring Resource: | Structured - sufficient |
| Species Comments: | Reintroduction and ongoing conservation of Large Blue is a huge success; reintroductions to two landscapes, the Poldens and Cotswolds, have thrived due to positive partnership working. |
Key Actions
Key Action 1
Proposed Action: Increase advice and support to landowners, advisors, land managers across all sites where Large Blue has been reintroduced and where also now naturally colonising within the two established landscapes, to secure long-term persistence and update advice as results of scientific research become available.
Action targets: 7. Best approach adopted at appropriate scales
Action type: Advice & Support
Duration: >10 years
Scale of Implementation: ≤ 100 sites
High priority sites: Poldens and Cotswolds
Comments: Our consulted expert requested we make it clear that persistence can be put under immediate threat if a sudden change in grazing or infrastructure/personnel occurs
Key Action 2
Proposed Action: Undertake research to establish methods to maintain suitability and longevity of sites in existing landscapes (micro-climate buffering) and opportunities for currently cooler landscapes that could become suitable in the future under increased temperatures and extreme weather events due to climate change.
Action targets: 5. Remedial action identified
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: ≤ 50 sites
High priority sites:
Comments:
Key Action 3
Proposed Action: Undertake further research to assess suitability of new potential landscapes and revaluate previously occupied/attempted landscapes (i.e. North Atlantic Coast, Dartmoor) for re/introduction potential.
Action targets: 6. Recovery solutions trialled
Action type: Scientific research
Duration: >10 years
Scale of Implementation: ≤ 100 sites
High priority sites:
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.