Specimens have also been reared from the cones of the exotic species Larix decidua The larvae normally pupate within the stem of their host plant.

The wingspan of adults of this species is between 20 and 30 mm with the forewings being blackish, variably overlain with reddish and whitish scales.

This species was described by Cajetan von Felder and Alois Friedrich Rogenhofer in 1875 and named Atychia illita.

[4] George Hudson also discussed this species using that name in his 1928 book The butterflies and moths of New Zealand.

[1] The male holotype specimen of H. illita, collected by T. R. Oxley in Nelson, is held at the Natural History Museum, London.

The forewings are very rich dark brown, thinly speckled with elongate bluish-white scales; there are usually cloudy discal marks before and beyond the middle, and a darker curved terminal band.

The hindwings are rich velvety-black, with two unequal elongate-triangular bright orange-yellow marks, and a cloud of minute yellow dots near the tornus.

[5]The wingspan is 20–30 mm with the forewings being blackish, variably overlain with reddish and whitish scales.

[1] This species is variable in appearance with some specimens having a rich reddish brown forewings without markings.