Orocrambus angustipennis is a moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

 of the Crambinae

Crambinae

Crambinae is a large subfamily of the lepidopteran family Crambidae, the crambid snout moths. It currently includes over 1,800 species worldwide. The larvae are root feeders or stem borers, mostly on grasses. A few species are pests of sod grasses, maize, sugar cane, rice, and other Poaceae...

 family. It is known from New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, where it is known from the North Island, South Island and the Chatham Islands.

The wingspan

Wingspan

The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

 is 34-40 mm for males and 44-50 mm for females. Adults are on wing from November to March in two generations per year.

The larvae feed on Cortaderia

Cortaderia

Cortaderia is a genus of 20-25 species of grasses in the family Poaceae. Members of the genus are native to South America , New Zealand and New Guinea . The name of the genus is derived from the Argentine Spanish word cortadera, which in turn refers to the sharp serrations on the leaves....

, including Cortaderia selloana and Cortaderia toetoe. They feed within growing stems and blades.