Aromia moschata (Linnaeus, 1758)
POLYPHAGA Emery, 1886
CHRYSOMELOIDEA Latreille, 1802
CERAMBYCINAE Latreille, 1802
CALLICHROMATINI Swainson, 1840
AROMIA Audinet-Serville, 1833
This is the only northern European member of a small Palaearctic genus of about 10 species of strikingly beautiful cerambycids. The musk beetle is widespread and common throughout most of continental Europe and North Africa, and extends east through Asia Minor and much of central and southern Asia to Japan. The species is very variable and about 30 subspecies have been recognized, and within these many aberrations have been described. The uniformly metallic green form that is widespread in the north is in some sense atypical; this uniform colouration varies from green to bronze and brilliant blue and most subspecies occur in an entirely black form, but many regional forms have the pronotum red, as is more normal for the genus e.g. the eastern Asian A. bungii (Faldermann, 1835) is known as the Red-necked longhorn beetle. Among A. moschata there are many beautiful regional forms but among the most striking must be some aberrations of the eastern European A. m. ambrosiaca (Steven, 1809), a metallic green insect with metallic purple appendages and a red pronotum with the disc and anterior margins to varying extents metallic blue, mauve or purple. In the U.K. it is very localized, although sometimes common where it occurs, throughout England and Wales and there are a few records from southern Scotland but there is no doubt that it has declined in recent decades. The typical habitats are wetland and marginal situations with an abundance of the host; various species of willow e.g. Salix caprea or S. viminalis, adults occur from June or July until late August, they are nocturnal as well as diurnal and often found visiting umbel flowers (apiaciae) in meadows etc. near to the hosts, or attracted to sap on damaged trunks. On hot days they may be observed in flight around or among the branches of stands of willow along river banks, and are supposed to be detectable by a characteristic musky smell on the leaves. The life cycle takes three years to complete; eggs are laid in crevices on trunks or stout branches and the young larvae bore into the bark leaving trails of fine powdery frass and wood dust. They initially feed below the bark but as they grow they bore deeper into the sap-wood, finally entering the xylem and boring upwards to produce vertical tunnels thirty or forty cm long. Fully grown larvae bore out towards the surface and construct a pupal gallery just below the bark, the entrance is sealed with wood pulp and the gallery lined with tiny wood shavings, pupation occurs in May or June with the large pale pupa resting upside down in the gallery, and adults eclose within six to eight weeks.
U.K. specimens are usually entirely metallic green, often with a bronze reflection, and at 13-34mm are very unlikely to be confused with any other species e.g. Oedemera nobilis or Lytta, but in any case the length of the antennae is very distinctive; in the male much longer than the body and in the female reaching at least to the elytral apex.
Elongate with rather parallel-sided elytra, the dorsal surface glabrous and only weakly convex, the ventral surface with dense pale pubescence. Head elongate with a variable median groove on the vertex, surface rugose and finely punctured. Eyes narrow and curved around the antennal insertions. Mandibles robust, each with a strong tooth on the inner margin. Antennae 11-segmented; the second segment small, the remainder elongate; 1-7 cylindrical and 8-11 flattened. Pronotum quadrate to transverse with a pair of large and sharp lateral teeth and variously convex either side of the disc, surface winkled and rather strongly punctured (in U.K. specimens at least, in some European subspecies it is smooth and shiny). Scutellum large and with a variously developed median furrow. Elytra long with prominent shoulders and two distinct, at least in the basal half, longitudinal carinae, the surface densely rugose and the apices separately rounded. Fully winged. Legs long and robust, especially the hind pair, usually concolorous with the body but sometimes contrasting blue or black. Typical specimens are entirely metallic green but often with a bronze lustre to various parts of the body and sometimes (rarely) entirely black. The size varies widely but most specimens are at least 25mm.