This species lives in open habitats and shrublands, at altitudes ranging from the low alpine zone down to sea-level.

However unlike both P. sequens and P. phricias, P. longstaffi has a large oval mark near the centre of the forewing.

[3][1] In 2017 Robert Hoare undertook a review of New Zealand Noctuinae and placed this species in the genus Physetica.

[1] The male holotype specimen was collected by Howes near Tomahawk Beach in Dunedin and is held at the Auckland War Memorial Museum.

Abdomen greyish-ochreous, lighter in colour towards anal tuft, which is light ochreous-grey.

[1] However unlike both P. sequens and P. phricias, P. longstaffi has a large oval mark near the centre of the forewing.

[5][6][1] This species lives in open habitats and shrublands, at altitudes ranging from the low alpine zone down to sea-level.

[1] They have also been collected on narrow leaved Dracophyllum but these specimens were reared to adulthood on plantain and chickweed.

[1] It has been hypothesised that species within the genus Dracophyllum might well be host plants but that the difficulty in keeping the offered foliage in good condition could be the reason for these deaths.

[1] It was also hypothesised that it is possible that larvae rest on species within the genus Dracophyllum in order to avoid parasitic wasps and flies that might otherwise be attracted by larval feeding.