Breck Robberfly (Machimus arthriticus)
Key Details
| Taxonomic Groups: | Invertebrate > insect - true fly (Diptera) > Soldier fly or ally |
| Red List Status: | Endangered (Not Relevant) [EN(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: | Machimus arthriticus |
| UKSI Recommended Authority: | (Zeller, 1840) |
| 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: | Confined to Suffolk Breckland centred on King's Forest nr. Thetford. Most records from 2002/2003 one record since from 2010. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | A defined habitat requirement is unknown. Records are from herb-rich heath and grassland on calcareous sand, including such areas within rides and clearings in conifer plantations. With a restricted location of which not all habitat will be suitable initial surveys to learn more and confirm populations and habitat associations would be useful to help identify more precise targeted actions. |
| 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: | Low - Life history factor/s |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Severely restricted in distribution (reportedly less the 40km2 of functional habitat). Appears to require herb-rich heath and grassland on calcareous sand, including such areas within rides and clearings in conifer plantations. Larvae are assumed to be predators in dry soil. Potential 4th action suggestion: Work on Forest Design plan to build better habitat linkages and to work on ride widening to support this species range extension. Factor in this species to the design plan, if not already present. |
Key Actions
Key Action 1
Proposed Action: Tailored surveys of potential habitat in known localities to determine the population and species distribution, thus identifying areas if M. artriticus is present.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 5 sites
High priority sites: West Suffolk, areas within King's Forest nr. Thetford and Home Heath, a single record from Cranwich Heath in Norfolk may be worth following up on.
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. As there is a large gap in records it would be pertinent to see if populations are still present and if so where they are within the range of habitats before specific actions can be identified.
Key Action 2
Proposed Action: Study of the biology and habitat needs at sites where populations are confirmed from Action 1 in an attempt to ascertain whether more targeted actions can be implemented to support these populations.
Action targets: 2. Biological status assessment exists
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: ≤ 5 sites
High priority sites: West Suffolk, areas within King's Forest nr. Thetford and Home Heath, a single record from Cranwich Heath in Norfolk may be worth following up on.
Comments: Needed to allow further surveys in potential sites and to allow more targeted approaches to protect existing populations.
Key Action 3
Proposed Action: No information on habitat or ecology is known but ongoing maintenance of short sparse grassland by allowing grazing of rabbits and sheep should be positive action.
Action targets: 2. Biological status assessment exists
Action type: Habitat management
Duration: >10 years
Scale of Implementation: ≤ 5 sites
High priority sites: West Suffolk, areas within King's Forest nr. Thetford and Home Heath, a single record from Cranwich Heath in Norfolk may be worth following up on.
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.