It is a large, conspicuous longhorn beetle attractive to the broad public due to its distinctive black and blue coloration. The beetle is typically considered as a montane (or sub-montane) species associated with European beech (Fagus sylvatica), although some lowland populations with different hosts have been identified. For the successful development, females oviposit eggs into the crevices and cracks of dead but still dry wood of broad-leaved trees. Larvae survive there for three to five years and pupate usually in the spring; adults exit the wood through typical elliptic holes. The activity period of adult beetles lasts each year from the end of June until September.
In the last century, the beetle has experienced significant declines, especially in the northern and central parts of Europe. For example, in the Czech Republic only three remaining localities now exist (NPR Velky a Maly Bezdez, CHKO Bile Karpaty, and game reserve Soutok). Thanks to that Rosalia longicorn became an endangered and strictly protected species in most of Europe. It is listed in the IUCN Red List of Threatened Species as vulnerable and in the EU Habitats Directive as a priority species of community interest. Because of the beetle‘s conservation status and general publicity, its role as an umbrella and flagship species providing protection for other beech-forest associated species has also been emphasized.
The main threat for this species is the loss of suitable habitats. Two contrary practices are usually involved. Intensive logging and massive dead-wood removal strongly affect the amount of breeding substrate available to Rosalia longicorn. On the other hand, a no management approach could lead to a closed canopy forest, which is also not suitable. Therefore, management at multiple scales is preferable, including regular forest thinning (coppicing, pollarding) and dead wood retaining.