Ichneutica atristriga

This species was described by Francis Walker in 1865 from specimens collected in Nelson and named Xylina atristriga.[2][3] The male lectotype specimen is held at the Natural History Museum, London.[3] In 1988 J. S. Dugdale, in his catalogue of New Zealand Lepidoptera, placed this species within the Tmetolophota genus.[3] In 2019 Robert Hoare undertook a major review of New Zealand Noctuidae.[4] During this review the genus Ichneutica was greatly expanded and the genus Tmetolophota was subsumed into that genus as a synonym.[4] As a result of this review, this species is now known as Ichneutica atristriga.[4]

Hoare described the larvae of this species as follows:

a pallid larva with the head capsule pale brown, broadly darker in a central stripe and laterally, prothorax tinged yellowish brown, a distinct dark-edged greyish mid-dorsal stripe, becoming poorly defined on the thorax, a dark subdorsal stripe on each side, thicker towards the anterior end of each segment and edged whitish below (only the whitish edging distinct on the thorax), and a greyish lateral stripe, again more poorly defined on the thorax.[4]

Observation of a live specimen of Ichneutica atristriga

Walker described the adults of this species as follows:

Male. Ferruginous-red. Palpi very slightly ascending, extending a little beyond the bead ; second joint fringed beneath ; third elongate-conical, full one-fourth of the length of the second. Antennae setose. Fore tegulae of the thorax with a slender dark cinereous-bordered band. Abdomen cinereous, with a tinge of fawn-colour, extending a little beyond the hind wings. Fore wings with a hoary irregular costal stripe, which extends from the base to five-sixths of the length, and partly contains the incompletely ferruginous-bordered orbicular and reniform marks ; a black streak proceeding from the base and ending behind the inner end of the orbicular mark, which is not oblique; a row of blackish points on the veins at half the distance between the reniform mark and the exterior border, which is slightly oblique. Hind wings aeneous; fringe paler, edged with whitish. Length of the body 9 lines; of the wings 22 lines.[2]

The adult male of this species has a wingspan of between 35 and 42 mm and the female has a wingspan of between 35 and 41 mm.[4] I. atristriga can possibly be confused with the smaller species I. propria.[4] However I. atristriga has thorax and forewings that have a pinkish tinge and I. propria has a dark streak on the discal part of the forewing which I. atristriga lacks.[4]

It is endemic to New Zealand.[5] I. atristriga is found through out the North, South and Stewart Islands.[4]

The adults of this species are on the wing from November to May.[4]

Poa cita, a larval host of I. atristriga

The life history of this species is in need of more detailed documentation.[4] The larval hosts likely include tussock grasses included Poa cita, P. colensoi and Festuca novae-zelandiae.[4] Larvae have been reared on species in the genera Bromus and Festuca.[4]

This species is regarded as being one of the most numerous noctuid species.[4] However Graham White recorded a population decrease of over 40% at two locations during the period from the early 1960s until the late 1980s.[6]