Variegated Fruit-fly (Phortica variegata)
Key Details
| Taxonomic Groups: | Invertebrate > insect - true fly (Diptera) > Fly |
| Red List Status: | (Not Relevant) [(not listed)(nr)] |
| D5 Status: | |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | Amiota variegata |
| UKSI Recommended Name: | Phortica variegata |
| UKSI Recommended Authority: | (Fallén, 1823) |
| 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: | The fly appears to be widespread in the South-east of England however the actual area of occupancy may be limited by habitat requirements although Palfreyman, J. et al., 2017 suggest that the range may open to expansion. More exploratory work is needed to track changes in population/distribution. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Scientific study to ascertain exact habitats and biological requirements; ongoing surveys for the flies and Cossus infected oaks to build a picture of the flies needs and to explore larval development requirements. |
| 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: | This species would not benefit from untargeted management |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Medium-high |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | The fly is associated with sap runs in Oaks (Quercus) infected by Goat Moth (Cossus cossus) although a definite direct link has not been proved. The adult flight period is later in the year, late August-September. |
Key Actions
Key Action 1
Proposed Action: Surveys of known and potential areas of interest in the South and South-east of England at known adult flight times. The 2015 report by Falk makes suggestion in line with this, see Action comments
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 50 sites
High priority sites: Most recent records are from Stubbs Wood, Hampshire (SU356039) Ashridge, Buckinghamshire (SP974133), Ashridge Commons and Woods SSSI, Hertfordshire (SP712120) Rushmere CP, Bedfordshire (SP9128), Ashampstead Common, Berkshire SU582748)Predicted sites for P. variegata were made (Palfreyman, 2018). Surveys were carried out in 2014 and site details with records prior to this were included, details in Falk, S., (2015) Surveys of Phortica variegata (Diptera: Drosphilidae) in 2014 with a compilation of other recent records. Buglife (Unpublished).
Comments: The fly is associated with sap runs in Oaks (Quercus) infected by Goat Moth (Cossus cossus) although a definite direct link has not been proved. Surveying in the vicinity of these trees using sweep nets and visual observation was most effective in the 2014 study. Utilisation of Dipterist's Forum may be a good approach asking for surveys of suitable trees in the most likely areas. Should deploy smelly fruit baited traps in the area too to lure adult flies. Too hit and miss with active trapping. There should be use of the moth datasets to locate areas of Cossus presence as well.
Key Action 2
Proposed Action: Investigation into larva development to ascertain requirements and associations within the environment where the flies occur. Current knowledge assumes association with Oak and Cossus cossus this would be useful to confirm for future conservation actions.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: ≤ 50 sites
High priority sites: Most recent records are from Stubbs Wood, Hampshire (SU356039) Ashridge, Buckinghamshire (SP974133), Ashridge Commons and Woods SSSI, Hertfordshire (SP712120) Rushmere CP, Bedfordshire (SP9128), Ashampstead Common, Berkshire SU582748). Predicted sites for P. variegata were made Palfreyman (2018). Surveys were carried out in 2014 and site details with records prior to this were included, details in Falk, S., (2015) Surveys of Phortica variegata (Diptera: Drosphilidae) in 2014 with a compilation of other recent records. Buglife (Unpublished)
Comments: Surveys of suitable habitats within known range, exploring saps runs, fallen fruit, dead decaying wood and fungi - this may involve 'breeding out'.
Key Action 3
Proposed Action: Advice to landowners/managers for the retention of, and to prevent tidying up of, dead and diseased oak trees, as at this time, these are the only known (assumed) sites for larval development.
Action targets: 5. Remedial action identified
Action type: Advice & support
Duration: 3-5 years
Scale of Implementation: ≤ 50 sites
High priority sites: Most recent records are from Stubbs Wood, Hampshire (SU356039) Ashridge, Buckinghamshire (SP974133), Ashridge Commons and Woods SSSI, Hertfordshire (SP712120) Rushmere CP, Bedfordshire (SP9128), Ashampstead Common, Berkshire SU582748). Predicted sites for P. variegata were made (Palfreyman, 2018). Surveys were carried out in 2014 and site details with records prior to this were included, details in Falk, S., (2015) Surveys of Phortica variegata (Diptera: Drosphilidae) in 2014 with a compilation of other recent records. Buglife (Unpublished).
Comments: Advice to landowners and managers in relation to maintaining habitat through retaining old and diseased trees.
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.