I. hartii is similar in appearance to Ichneutica agrorastis but can be distinguished as it tends to be smaller in size and have a more purplish shade to its fore wings.

It is attracted to light and the adults of this moth are on the wing between January and March.

This species was first described by W. G. Howes in 1914 from a single male specimen obtained by Mr S. Hart near Cape Egmont Lighthouse.

[4] In 2019 Robert Hoare undertook a major review of New Zealand Noctuidae species.

Forewings covered with dull silvery (lead-coloured) scales, the rather indistinct lines being bright rufous.

Two distinct marks on costa close to base, being portion of a broken indistinct line across wing.

A very distinct line crosses between reniform and orbicular, running straight across save for a slight outward bend at wing-centre.

[3] This species can be found in lowland native forest as well as in hill ranges up to approximately 800m in altitude.