New Zealand Red Admiral

The red admiral has a wingspan of around 50–60 mm (2.0–2.4 in). The top side of the forewings are mostly black, with a central bright red bar running back from the front edge. There are blue spots and white spots, fringed with light blue, near the forewing tips. The rear wings have a background colour of dark reddish brown with a red patch containing four black circles, and the centre of each circle has a pale blue dot. The extent of brown colouring varies somewhat, some individuals having a pale brown to near-white background colour at the base of the rear wings and tip of forewings. The underside of the rear wings is a mottled collection of white, brown and black shapes, which camouflages the butterfly when at rest. The two subspecies of the red admiral are very similar and difficult to distinguish, although the red marking of the hind wing is less extensive in the mainland subspecies than in the Chatham Islands subspecies. The rear margin of the hind wing is also more wavy in the mainland subspecies. The red admiral is somewhat similar to the yellow admiral (Vanessa itea), which overlaps with it in distribution and is frequently found with it. They are easily distinguished by the red-orange markings of the forewing whereas the yellow admiral forewings are distinctly yellowish.

Juvenile stages. The barrel-shaped egg is green and has nine ribs that run from top to bottom. …

The red admiral is relatively common throughout most of New Zealand, including on Stewart Island. The Chatham Islands subspecies is widespread on Chatham Island and Pitt Island, the second largest island in the group. The species can be found in a variety of habitats, including suburban gardens, forests and on mountains.

The primary host plant for red admiral caterpillar is the native stinging nettle, also known as ongaonga (Urtica ferox), although the caterpillar can also eat other Urtica species such as Urtica incisa. In a study where the red admiral was presented with several species of Urtica to lay eggs on, it was found to preferentially lay eggs on Urtica ferox. When the caterpillar was grown on this species, it was generally heavier than when grown on other species, indicating that it was an optimal food source for the caterpillar. This was suggested to be an example of the preference-performance hypothesis, where a species will preferentially lay eggs on plants that are most suitable. The Chatham Islands subspecies is reported to use Urtica australis as a host plant instead. As an adult, the red admiral feeds on flower nectar from several species and on the sap of Nothofagus (southern beech) trees.

The mainland subspecies is commonly referred to as the red admiral or New Zealand red admiral, whereas the Chatham Islands subspecies is referred to as the Chatham Island red admiral. Vanessa gonerilla is also referred to as kahukura in the indigenous Māori language. The word kahukura is derived from kakahu and hura, which mean "garment" and "red", respectively. The genus name Vanessa is likely derived from the character of the same name in the poem "Cadenus and Vanessa" by Jonathan Swift.