Ischalis nelsonaria, also known as the angled fern looper, is a species of moth of the family Geometridae. It was first described in 1875. This species is endemic to New Zealand and has been observed in both the North and South Islands. I. nelsonaria inhabits native forest. The larval host of this species is Zealandia pustulata. Larvae have also been raised on Blechnum novae-zelandiae. Adult moths of this species are variable in appearance and are nocturnal. They have been observed on the wing throughout the year but are most frequently observed in February and March. They have been observed feeding on the flowers of Metrosideros diffusa.

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