Ichneutica blenheimensis

A. V. Chappell described the egg as follows:

Pale cream; light brownish with brown ring and central spot on the top; dark brown; pale blackish; finely sculptured. A. V. Chappell also described the larva as follows:

Pale dusky yellow; transparent; numerous stout black hairs rising singly from black spots; head large, pale amber speckled with black. Hudson described the adults of this species as follows:

The expansion of the wings is about 1+1⁄2 inches. The fore-wings are cream-coloured with the veins darker; there are three faint black dots at about one-third, a curved series of black dots near the termen, the termen itself being strongly shaded with dark greyish-brown; the cilia are dark greyish- brown. The hind-wings are grey, paler towards the base; the cilia are also grey.The wingspan of the adult male is between 37 mm and the female wingspan is between 40 and 41 mm. The blackish forewing fringes are diagnostic of this species. Worn specimens of I. arotis can be confused with worn specimens of I. blenheimensis. However I. arotis can be distinguished from I. blenheimensis as it has a scale-tuft on the thorax and dark longitudinal stripes on the tegula.

This species is endemic to New Zealand. It is found throughout the North, South and the Stewart Islands. The range of this species covers the Hawkes Bay, Marlborough, Dunedin, Otago Lakes, Southland and the Stewart Island regions. Along with the type locality of Meanee, specimens have also been collected at the Denniston plateau, Blenheim, Dunedin, Lake Wakatipu and Routeburn.

This species is on the wing from November to March. It has been collected via sugar traps and is attracted to light.