In Micó and Galante (2002) this species is known as Cetonischema aeruginosa.

European regional assessment: listed as Near Threatened because this species is very rare throughout its range and is declining in many parts. Its habitat is old trees and dead wood which are often removed and this leads to habitat loss and fragmentation.

EU 27 regional assessment: listed as Near Threatened because this species is very rare throughout its range and is declining in many parts. Its habitat is old trees and dead wood which are often removed and this leads to habitat loss and fragmentation.

This species is widespread in southern, central and eastern Europe, and present in the north as well. Sub-fossil material has been found in a peat-bog in Denmark where the species no longer occurs (Paulian and Baraud 1982).

In eastern Europe it occurs from south Belarus, middle Russia to Ural (on east). In Ukraine it lives in forests and in the northern part of forest-steppe zones. In Hungary the species is widespread in the hilly and mountainous areas and in the lowlands where extensive forests occur. In Romania it is widespread in all regions, from lowland with grass and small forests up to the low mountains. In Italy it is present in mainland and Sicily.

In Cyprus Protaetia aeruginosa does not occur; it was reported from Cyprus erroneously as a result of misidentification of Protaetia (Cetonischema) speciosa (C. Makris pers. comm. 2009). Cetonischema speciosa marchei has been described as an endemic subspecies of Cyprus (Alexis and Delpont 1999).

This species appears to be rare over much of its European range and, although the overall population trend remains unknown, it is known that it is declining in some parts while increasing in others. There is recent evidence that it is not as rare as previously thought, in some areas at least, once appropriate trapping techniques have been applied. However, hollow trees are known to be becoming increasingly scarce across Europe and so a downward trend in abundance and number of localities may be expected to be occurring.

The population size and trend have not been quantified in Hungary, although the species is regarded as common in its localities. In Romania there are large populations where old forest and meadows are still present - the species needs bright oak forest (P. Istrate pers. comm. 2009). In France the the use of window traps and traps with wine placed at high level in old oaks has resulted in the recent discovery of new populations (R. Allemand pers. comm. 2009).This species is extremely rare in the Iberian Peninsula where rarity is probably related to the decline of the forests they inhabit, and the current distribution is probably a relict population of a formerly much greater range. In Greece it is currently rare and continues declining. In the Czech Republic it is rather rare and is only occurring in a few areas, but although the species is very rare, it is expanding. There is no population data for Italy. In Ukraine it is rare.

This is an obligate saproxylic species. The larvae develop in wood mould in the base of hollow living trees, usually in the trunks and main boughs with large cavities containing large volumes of wood mould, primarily derived from natural fungal decay of the dead heartwood. Suitable cavities may occur high up the host trees. Larvae normally take two years to develop, longer where conditions are not optimal. Suitable trees may occur in a wide variety of situations, all places where trees have been retained into maturity and old age, for a variety of reasons. The adults are active in V-IX, fly during warm days, and are very attracted by sap-runs; they usually live in the canopy of trees.

In central Europe it is linked to thermophilous oak forests. In Hungary it occurs in various broad-leaved forests types where hollow trunks are abundant; especially frequent in riverine willow galleries (O. Merkl pers. comm. 2009). In Romania it occurs especially where there are a lot of old oaks with large hollows. In France this species in found only in large broad-leaved forests in plains (Paulian and Baraud 1982). In Spain it is linked to large forested areas of deciduous species in which their larvae develop. In Ukraine larvae develop in stubs and decayed wood of oak and fruit trees;  in old forests and gardens, the adults are rarely found at flowers.

Removal of old trees and habitat fragmentation are major threats to this species, for example in Spain. Also the excessive use of insecticides is a local threat (Greece). In Ukraine the destruction of old trees, where larvae develop, are posing a threat to P. aeruginosa. In Hungary, although removing dead wood occurs in several localities, the species does not seem to be threatened; invasive trees in riverine galleries are more dangerous.

Saproxylic Coleoptera tend to be popular with beetle collectors although trade is rarely an issue, the only exceptions being a few larger species of more dramatic form or colour.

Habitat continuity and connectivity are required. It lives in several protected areas (e.g. Hungary). The species is legally protected in Hungary. It is listed as Endangered in Germany (2009) and the Czech Republic.