A beetle that had not been recorded in Wales for 60 years has been found breeding in Pembrokeshire.
Surveyors working at Castlemartin Range have found larvae of the Short-Necked Oil Beetle on a small area of the site, three years into a search for it. Natural Resources Wales said the number and distribution of the larvae suggested the surveyors had come across some of the hatchlings from a larger batch of immature beetles.
Last year's survey at the same site found only dead adults, raising concerns about the species' future there.
Anne Hobbs, of the Bumblebee Conservation Trust, said it was "very exciting" that the evidence suggested the species was breeding in Wales again. She thanked partners and volunteers for their continued support through two years without a larval sighting, and called the beetle an "amazing creature".
The species was not reported anywhere in the UK for almost 60 years after 1948, as habitat loss brought it to the brink of extinction. It was rediscovered in Devon in 2006 and on the Isle of Coll in 2009, and populations have since been found on Tiree, Islay, Barra and Uist.
It is classed as nationally rare within Great Britain and listed as vulnerable on the IUCN Red List. Castlemartin Range is currently the only place in Wales where the species is found, and is consistently surveyed by conservationists.
The beetle depends on solitary bees for its lifecycle and needs a particular habitat, with thick vegetation for shelter and dense flower coverage both essential. Natural Resources Wales said those conditions mean there are only a handful of suitable sites in the UK. The project is part of Wales's "flagship species recovery programme".
Adults can grow up to 24mm, or 0.9in, in length, and the lifespan of an adult is approximately one year. They can typically be found from March to June, in flower-rich coastal grassland and sand dune habitat, and are most active on warm, sunny days.
It is worth setting out what the sixty-year gap describes. An adult Short-Necked Oil Beetle lives about one year. No beetle was absent from Wales for sixty years. No beetle was absent for more than one.
What lasted sixty years was the not-finding. This newspaper would like to be clear that this is a different quantity, measured in a different unit, by a different animal.
The conditions of measurement are also now on the record. The beetle is detectable for four months of the year, in flower-rich coastal grassland, on warm and sunny days, at a handful of sites, by people who have gone to look. Our analysts calculate that the species is therefore absent for eight months a year as a matter of definition, and present only when it is simultaneously sunny and observed.
Three years of searching at Castlemartin produced dead adults in one year and larvae in the next. Nothing in the record suggests the beetle became more numerous between those two surveys. It became more documented, which in Great Britain is the difference between vulnerable and extinct.
The Department of Unnecessary Research congratulates the volunteers and notes one consequence for the national list. Britain's extinct invertebrates are, on the present evidence, those that have not yet been looked for on a warm day.