What it is
An obligate saproxylic scarab (Osmoderma eremita) of hollow broadleaf trees. Adults rarely fly far; populations sit inside single trees or tiny tree groups for generations.
Range
Europe and the EU27. The extent of occurrence is large, but the area of occupancy for breeding sites is estimated at only about 2,000-2,500 km², and those sites are severely fragmented.
What happened
Stag beetle larvae need a volume of moist deadwood. Hermit beetles need a cavity that holds wood mould, and the next generation of hollows is decades behind the trees being lost now. Because adults rarely fly far, a gap between veteran trees can isolate a population for generations.
When / status
IUCN (2023): Near Threatened, B2ab(ii,iii,v). Old hollow trees are in continuous decline, with a long regeneration lag.
Human role
Felling veteran hollow trees, and failing to keep the next generation of cavities, removes the only places this beetle can breed.
Sources
IUCN Red List (Osmoderma eremita, Near Threatened, 2023).