Sestra flexata

S. flexata was first described by Francis Walker in 1862 using specimens collected either in Auckland by D. Bolton.[4] Walker originally named the species Cidaria flexata.[2] George Hudson discussed and illustrated this species in his 1928 book The butterflies and moths of New Zealand.[5] The male holotype is held at the Natural History Museum, London.[2]

The pale yellow egg is cylindrical in shape.[6] The larva of this species is coloured dark brown and is 25 to 30 mm long when mature.[7] The larvae is approximately 1 to 1+1⁄4 inch long and is a brownish greenish colour with yellow tones underneath. Down its back is a brown line with two more lines down its sides. It also has a few black markings and a number of short bristles.[6]

Walker described the adult of this species as follows:

Female. Cinereous fawn-colour, ochraceous beneath. Palpi slender, very short, obliquely ascending. Abdomen yellowish. Forewings acute, subfalcate, with a blackish shade on nearly half the middle space and along the exterior border, which is distinctly angular. Hind wings yellowish, without markings; fore part of the exterior border slightly truncated. Length of the body 6 lines; of the wings 16 lines.[4]

Hudson described the adults of this species as follows:

The expansion of the wings is from 1+1⁄4 to 1+3⁄8 inches. The fore-wings are pale plum-colour; there is an indistinct, curved, brownish transverse line near the base; a straight dark brown line across the middle, and a curved series of brownish dots beyond the middle; the apex is pointed, and the termen has a strong projection a little above the middle. The hind-wings are ochreous, with a series of minute brownish dots across the middle.[5]

This species is endemic to New Zealand.[1] This species is found throughout New Zealand including the North, South, Stewart and Chatham Islands.[6]

The larval hosts of this species are Pteris macilenta and Histiopteris incisa.[7] It has been collected by beating the latter fern.[6]

The older larvae of this species feed at night.[7] When disturbed the larva will drop to the ground.[7] Adults of this species pollinate Leptospermum scoparium.[8] The adult moths are nocturnal, are attracted to light and on the wing from September until March.[7][6]