Last year, the survey at Castlemartin found only dead adults of this particular beetle, raising concerns about the future of this species and its continued presence on the site.
But this year, after three years of searching, experts discovered larvae of the beetle on a small area of the site, suggesting that surveyors had managed to find some of the hatchlings from a larger batch of immature beetles.
The number and distribution of the beetle larvae seen also supported this, according to Natural Resources Wales (NRW).
The Short-Necked Oil Beetle is classed as nationally rare within Great Britain and listed as vulnerable on the IUCN Red List, external.
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.
Adults can grow up toe 24mm (0.9in) in length and the life span of an adult is approximately one year.
NRW said these conditions mean there are only a handful of suitable sites in the UK.
They were rediscovered in Devon in 2006 and on the Isle of Coll, in Scotland, in 2009. Since then, populations have been found on Tiree, Islay, Barra and Uist.
Castlemartin Range, in Pembrokeshire, is currently the only place in Wales where the species can be found and it is being consistently surveyed by conservationists.
The project is part of Wales’s “flagship species recovery programme”, said NRW, which works to conserve the Short-Necked Oil Beetle Sand other species that share similar habitats.
Hobbs described the Short-Necked Oil Beetle as an “amazing creature” and said their work needed to consider the “needs of several species to be effective”.
She thanked their partners and volunteers for their continued support, despite having two years without a larval sighting.
“We look forward to the continued management of the site so that this amazing species can survive now and into the future.”
