Science · Rare beetle breedingCastlemartin rare beetle: Larvae found after three-year searchWritten November 1, 2026 at 2:01 AM UTCWatchTranscript0:07Surveyors have found rare beetle larvae at Wales's only known site for the species.0:11Last year's search found only dead adults.0:13The young beetles now offer fresh evidence of breeding, but their survival depends0:16on a habitat shared with solitary bees.0:19The test is whether this isolated population can sustain future generations.0:23Castlemarton Range in Pembrokeshire holds the newly discovered larvae in a small0:27area.0:28Natural Resources Wales says their number and distribution suggest surveyors found0:32some hatchlings from a larger batch of immature beetles.0:34The discovery followed three years of searching.0:37Anne Hobbs from the Bumblebee Conservation Trust hanged partners and volunteers who0:41kept going through two years without a larval sighting.0:43Those gaps in sightings left conservationists concerned about the beetle's continued0:47presence.0:47Adult short-necked oil beetles can reach twenty four millimeters long.0:51They're usually encountered from March to June, and they're most active on warm,0:54sunny days.0:55Their habitat includes flower, rich coastal grassland, and sand dunes.0:59The species is classed as nationally rare in Great Britain and has a vulnerable1:03conservation listing.1:04Habitat loss has been a central threat.1:06Keeping the beetle here means maintaining the flowers it depends on and dense1:09vegetation where it can shelter.1:11One known Welsh location concentrates the conservation stakes at Castlemartin.1:15Elsewhere in Britain, populations have been recorded in South Devon and South1:19Wiltshire, and on the Scottish Islands of Kal, Tyree, Isle, Barra, and Weist.1:24After records in1948 , the beetle went unreported in the United Kingdom for almost1:29sixty years.1:30It was rediscovered in Devon in two thousand and six, then on Call in two thousand1:33and nine.1:34Wales also has a documented history before this latest find.1:37An adult was recorded at Linnee Head in June2015 .1:40In2020,2, surveyors found one dead adult and numerous larvae at Penn Way at Holt1:46Bay.1:46Those larvae confirmed breeding within the protected site then.1:49The20206 discovery renews that evidence.1:52The20202 larvae were triungulins, the mobile first stage of the beetle's life.1:57So searches here have found young beetles before.1:59The discouraging result from last year's survey belongs to a more recent chapter2:03when surveyors found only dead adults.2:05The larvae climb onto flowers and attach themselves to visiting solitary bees.2:09Those bees carry them into their nests.2:11The beetle depends completely on solitary bees to complete its life cycle, tying its2:15survival to another insect's habitat needs.2:17A patch of ground may provide shelter for adult beetles, but it also has to support2:21the bees and flowers their young need.2:23Protecting the species means keeping those relationships working across the habitat2:27beyond the spot where an individual beetle appears.2:29Dense flowers and sheltering vegetation are essential to this beetle's habitat.2:33Wales's flagship species recovery program includes the Castlemartin project, with2:38work intended to conserve the beetle alongside other species sharing the same2:41conditions.2:42Hobbs called the evidence of renewed breeding very exciting.2:45She also said conservation work needed to consider the needs of several species to2:49be effective.2:50The beetle's dependence on bees makes that a practical requirement for its survival.2:54Hobbs wants management of the site to continue so the species can survive into the2:57future.2:58Castle Martin continues to be surveyed, with the beetle's long-term prospects tied3:02to maintaining their habitat and the solitary bees they need.3:05The larvae suggest reproduction is happening again.3:08They don't yet show that the population is growing or that enough young beetles3:11survive to sustain it.3:12Continued survival depends on keeping the beetles, their bee hosts, and their3:16flowers together across successive generations.Read the articleStory timelineHeyDex
