Following a three-year search, conservationists have discovered the rare short-necked oil beetle breeding at the Castlemartin Range in Pembrokeshire, the only known site in Wales where the species exists.
The discovery brings a sense of relief after recent population surveys yielded only dead specimens, leading conservation workers to question whether the insect could maintain its foothold in the region. Surveys conducted in 2022 and 2025 recovered exclusively dead adults at the Pembrokeshire location, casting doubt on the insect’s viability.
Castlemartin Range Surveys Reveal New Larvae
The insect, scientifically known as Meloe brevicollis, depends completely on solitary bees to complete its reproductive cycle. Adult beetles grow up to 24mm (0.9in) in length and typically exhibit a one-year lifespan, emerging in flower-rich coastal grasslands and sand dunes during warm, sunny weather from March to June. These stringent biological requirements mean the UK hosts only a handful of suitable sites.
Despite previous setbacks, field checks in 2026 identified larvae within a localized section of the Castlemartin Range. Conservation teams interpret these findings as evidence of hatchlings emerging from a larger batch of immature beetles, confirming that reproduction is actively occurring.
Bumblebee Conservation Trust Leads Habitat Management
Monitoring work at the Pembrokeshire site is carried out by the Bumblebee Conservation Trust as part of its Shrill Carder Bee initiative. Financial backing comes from The National Lottery Heritage Fund, supporting Wales’s wider Natur am Byth flagship species recovery programme.
The beetle’s unique lifecycle requires a delicate combination of bare earth for egg deposition, dense flowering plants for reproduction, and thick vegetation for cover. Newly hatched larvae, known as triungulins, attach themselves to visiting flower bees to reach their nests, where they feed on stored pollen.
It was very exciting to find this species and evidence of its breeding again, especially considering it will be the last survey for the species for our project.
Anna Hobbs, project delivery officer for the Bumblebee Conservation Trust
Broader Conservation Efforts Across the UK
Historical records show the species was rediscovered in Devon in 2006 and on Scotland’s Isle of Coll in 2009. Subsequent fieldwork has located populations across Tiree, Islay, Barra, and Uist, leaving the Castlemartin Range as the sole known home for the insect in Wales.
Project organizers emphasize that protecting the beetle requires safeguarding its entire ecosystem, which also supports flora such as the Goldilocks Aster and Pale Dog Violet alongside the Shrill Carder Bee.
We are very grateful to our partners and volunteers for persevering with us after two years without larval sightings and look forward to the continued management of the site so that this amazing species can survive now and into the future.
Anna Hobbs, project delivery officer for the Bumblebee Conservation Trust