[1][2] This species is endemic to New Zealand and is only found in the South Island, in and around the Southern Alps.

Male I. cornuta can be distinguished as it has longer pectinations on the antennae and the female lacks the dark scaling that can be found on the thorax of the I. arotis.

[2] There are also slight visual differences in the colour patterns on the forewings of the two species.

[2] The range of these two species do overlap in such areas as Arthur's Pass and in the Otago Lakes region.

[2] This species is endemic to New Zealand and is only found in the South Island, in the foothills of the Southern Alps.