Twin-spotted Major (Oxycera leonina)
Key Details
| Taxonomic Groups: | Invertebrate > insect - true fly (Diptera) > Soldier fly or ally |
| Red List Status: | Vulnerable (Not Relevant) [VU(nr)] |
| D5 Status: | Included in the baseline Red List Index for England (Wilkins, Wilson & Brown, 2022) |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Oxycera leonina |
| UKSI Recommended Authority: | (Panzer, [1798]) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Drake, 2017 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Discovered in 1989, two main sites predominating and a sprinkling of records around these, Norfolk and E. Suffolk. Habitat requirement seems fairly common although distribution is limited, this may indicate more specific (unknown) requirements. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Few recent records going back to 2017, a single record from 2003. The latest records from one of the main sites are from 1997 so further exploration of this is needed to confirm if the species is still occupying this habitat. |
| 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: | Potentially wider scale management of the landscape to maintain water levels within the known sites, transitional habitat between wet peat and dry sand appears to be important on several sites. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Low - Relict or natural rarity |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Larvae are assumed to be terrestrial or semi-aquatic requiring damp soil with remnants of decaying vegetation (transition between peat and sandy soil may be necessary for larval development but this needs confirming) . The adults are straightforward to recognise, so if surveying is taking place at the right time of year then they should be noticed. Previous records give a good idea of where to look within any sites that are surveyed. Adults have been swept from Alder and Sallow alongside gently sloping banks of streams at several sites. |
Key Actions
Key Action 1
Proposed Action: Tailored surveys of the required habitat in the adult flight period to be completely sure whether the previous populations are present before more specific targeted actions may be implemented.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites: W.Norfolk, Santon Downham Common (TL814883), Lynford Meadow (TL821936), Lynford Arboretum (TL82219453), East Walton Common (TF735164). There are also two records from Shottisham in Suffolk, although the grid reference given may be a little east of the most likely site by the River Deben (TM31454358)
Comments: A tailored survey within the known flight period to encompass the areas where previous sightings have been made along with any adjacent/linked areas with similar habitats to see if populations are still present or if they have spread.
Key Action 2
Proposed Action: Following on from initial surveys on sites where populations are confirmed, research aimed at understanding the exact habitat requirements to allow more precise actions in relation to larval requirements would be beneficial.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites: W.Norfolk, Santon Downham Common (TL814883), Lynford Meadow (TL821936), Lynford Arboretum (TL82219453), East Walton Common (TF735164). There are also two records from Shottisham in Suffolk, although the grid reference given may be a little east of the most likely site by the River Deben (TM31454358). Any other sites discovered during initial surveying
Comments: As conservation and habitat requirements are not completely understood, any advance in knowledge re. larval requirements should be beneficial.
Key Action 3
Proposed Action: Liaising with local landowners and farmers in relation to water abstraction especially and slurry, run-off and potential of ingress by avermectins and other harmful chemicals all of which may lead to loss of populations.
Action targets: 4. Autecology and pressures understood
Action type: Pressure mitigation
Duration: >10 years
Scale of Implementation: ≤ 10 sites
High priority sites: W.Norfolk, Santon Downham Common (TL814883), Lynford Meadow (TL821936), Lynford Arboretum (TL82219453), East Walton Common (TF735164). There are also two records from Shottisham in Suffolk, although the grid reference given may be a little east of the most likely site by the River Deben (TM31454358). Any other sites discovered during initial surveying
Comments: The assumed damp transitional substrate requires water levels to be maintained, if larvae are in these wet substrates, then there may be a risk from agricultural run-off and ingress of pesticides.
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.