Pasiphila plinthina is a moth in the family Geometridae. It is endemic to New Zealand. P. plinthina is on the wing mainly from June until September with occasional observations up to December, and as such it is regarded as a winter specialist.[7] P. plinthina are attracted to light.[8] Hudson explained that this species could sometimes be found resting on tree trunks but that it was more often collected when dislodged from foliage
This species is similar in appearance to P. sandycias with which is has been confused.[5] It can be distinguished from this species as its palpi are longer and has more blurred forewing markings