This species was first described by Edward Meyrick in 1905 using specimens collected at Otira Gorge and Wellington and named Orthenches drosochalca.

[2] The male lectotype, collected by George Hudson in Wellington, is held at the Natural History Museum, London.

Palpi dark fuscous, inwardly and towards base white, terminal joint half as long again as second (1+1⁄2).

Fore-wings elongate, costa moderately arched, apex pointed, termen sinuate, rather strongly oblique, rounded beneath; 7 to termen; shining coppery-bronze; four oblique fasciae of white irroration, first slender, second antemedian, broader, third angulated, considerably enlarged towards costa, fourth forming an apical patch extended along termen; a spot on base of costa, an interrupted streak along submedian fold, and a spot above middle of disc purple; a dark fuscous-purple transverse mark in disc at 2⁄3, in third fascia : cilia light grey, above apex spotted basally with purplish.

Hind-wings ovate-lanceolate, apex acute, termen sinuate; light grey, darker posteriorly; cilia whitish-grey.

[5] It can be distinguished from similar appearing species as its forewings have very scattered white scales as well as a more brassy foreground colour.