Rosalia Longicorn

• It is listed in Annexes II and IV of the European Union Habitats Directive, which requires its populations and its habitat to be protected across Europe.
• It depends on large-diameter dead wood: tidy, intensively managed beech woods, with no old trees and no fallen trunks, wipe it out.
• The adults will lay their eggs in stacked firewood, and logs that are later moved or burnt become death traps for the species.
• It is one of the most striking insects in Europe: bluish grey with velvety black patches and extremely long, ringed antennae.
• It depends on old, dead or dying, well-lit beeches, a resource that modern forestry systematically removes. That is its conservation problem — not a lack of forest but a lack of old forest.
• It is protected under the European Union's Habitats Directive as a priority species, and its presence shapes forest management in many mountain areas.
• The larva takes between two and three years to develop inside the wood.
• In Spain it is rare and highly localised, above all in the beechwoods of the north and in a few populations in the Sistema Ibérico.
• The adults fly in summer and are seen on sunlit trunks and woodpiles, which makes them vulnerable to the removal of dead wood.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Mature montane beech woods with plenty of dead wood

Sexual maturity

The adults settle on flowers by day and feed on pollen; they produce sound by rubbing their elytra with their hind legs

Gestation / incubation

After mating the female lays the eggs in a crack in the bark of a beech; the larva develops in the dead wood for 2-4 years, pupates in spring or early summer and the adult emerges between June and July

Litter / clutch size

The eggs are laid one by one in hollows and cracks in the bark of old, dead or weakened beeches

Sources consulted: https://es.wikipedia.org/wiki/Rosalia_alpina; Ficha de especie de Rosalia alpina; Generalitat de Catalunya; Lista Roja UICN via fichas de especie; MITECO; MITECO, bases ecologicas para la conservacion (Mayet 1890, Vives 1996); Parque Natural del Moncayo; Generalitat de Catalunya, Medi Ambient i Sostenibilitat; Asturnatura, ficha Rosalia alpina; MITECO, bases ecologicas para la conservacion de especies de interes comunitario; Asturnatura; Naturayala

Best time: Seen from May to October, peaking from mid-July and through August, on the hottest days, on the thick trunks of old or dead trees in damp beech woods