Scarce Grey Flag (Hydropsyche bulgaromanorum)
Key Details
| Taxonomic Groups: | Invertebrate > insect - caddis fly (Trichoptera) > Caddisfly |
| Red List Status: | Critically Endangered (Not Relevant) [CR(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: | Hydropsyche bulgaromanorum |
| UKSI Recommended Authority: | Malicky, 1977 |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Wallace, 2016 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | There is only one site (lower River Arun in Sussex) and it is restricted at that site hence the IUCN grading. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Increasing the amount of the specific gravel habitat that this species needs is desirable (but probably impossible at its existing site). |
| 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: | An extremely rare species with specific habitat needs. |
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: | This is a very rare species and with a specific habitat requirement so general diversification of rivers would be of no value. Freshwater abstraction that alters the location of the brackish / freshwater boundary is a threat and may need mitigation as it is the place where this species lives. |
Key Actions
Key Action 1
Proposed Action: Re-survey the lower River Arun to see if there has been a change of distribution of the caddis or its habitat since the Martin Dake survey. Survey the lower River Arun to map where the larvae are found and note the substratum they occupy.
Action targets: 4. Autecology and pressures understood
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: 1 site
High priority sites: lower River Arun
Comments: Necessary to plan habitat enhancement
Key Action 2
Proposed Action: Undertake a desk-top study of the habitat used by this species to see if there is a chance to enhance the amount of habitat in the River Arun. Rivers that could be considered for translocation but that would be very expensive and might not success so has not been suggested as an action. Action 1 is designed to find the micro-habitats used and these would be the target for enhancement of that habitat and effectiveness of the method would be monitored.
Action targets: 6. Recovery solutions trialled
Action type: Habitat creation
Duration: 1 year
Scale of Implementation: 1 site
High priority sites:
Comments:
Key Action 3
Proposed Action: Obtain a full mitochondrial DNA profile to enable any new populations that arise to be assessed as either arising from native stock or a new arrival
Action targets: 2. Biological status assessment exists
Action type: Scientific research
Duration: 1 year
Scale of Implementation: 1 site
High priority sites:
Comments: This species is increasing on the continent and has made distribution jumps into Scandinavia that exceed the width of the English Channel. The Action point is to enable any new populations that arise to be assessed as either arising from native stock or a new arrival as they may be treated in a different way with new immigrants being treated as of no interest from a conservation point of view.
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.