New Zealand Red Admiral

Fascinating facts about the New Zealand Red Admiral

• A New Zealand red admiral spreads its wings to roughly 50-60 mm (2.0-2.4 in). Its forewings are black with a bright red bar, blue and white spots edged in light blue, while the hind wings show a dark reddish-brown background punctuated by a red patch with four black circles each centred by a pale blue dot. The underside of the hind wing is a mottled mix of white, brown and black that camouflages the butterfly when it rests.
• From egg to adult, the red admiral can complete a generation in just over two months. Eggs are laid from September until late May, hatch after eight to ten days, and the caterpillar spends five to six weeks feeding and growing through five instars before pupating. The pupal stage lasts two to three weeks, after which the adult emerges, most abundantly in October. Because the species can produce two full generations per breeding season, and sometimes a third in favourable years, it is multivoltine.
• Native stinging nettle (Urtica ferox) is the red admiral's favourite nursery plant. In experiments offering several nettle species for egg-laying, females chose U. ferox most often, and caterpillars raised on it grew heavier than those on other hosts, confirming the preference-performance hypothesis that insects lay eggs where offspring will thrive. On the Chatham Islands the butterfly uses U. australis instead, showing flexibility in host choice across its range. This reliance on specific nettles means that loss of these plants, especially in suburban gardens, could limit breeding sites and contribute to perceived declines.
• Exotic wasps are a hidden threat to the red admiral, turning many pupae into rust-coloured shells. Surveys on Banks Peninsula found the Australian ichneumonid Echthromorpha intricatoria in 67.5-82.3 % of pupae, while the introduced pteromalid Pteromalus puparum infected 3.5-16.9 % of the same samples. Across Wellington, Canterbury and Dunedin regions, E. intricatoria showed a 67 % parasitism rate versus 8 % for P. puparum. Statistical models suggest these wasps suppress the butterfly by roughly 30 % (E. intricatoria) and 5 % (P. puparum) of the population. Such high mortality may explain anecdotal reports of decline despite the species being listed as "Not Threatened".
• The red admiral was among the first New Zealand insects ever described by science. Danish zoologist Johan Christian Fabricius named it Papilio gonerilla in 1775, using specimens collected on James Cook's first voyage, the second European visit to New Zealand. The original type specimens now sit in the Natural History Museum of London's Banks collection. Over the centuries the butterfly bounced between genera, landing in Vanessa after a 2005 genetic revision.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

At a glance

About the New Zealand Red Admiral

The New Zealand Red Admiral (Vanessa gonerilla) is a striking butterfly, easily recognized by its vibrant orange-red bands and black wings adorned with white spots. These butterflies exhibit sexual dimorphism; males are slightly smaller and more vivid in color, while females tend to have a darker hue. Typically found in forested areas, gardens, and scrublands across New Zealand, the Red Admiral thrives in environments rich in flowering plants. Their life cycle is closely tied to native plants, as the caterpillars primarily feed on the leaves of nettles, which are abundant in their habitat. The adults, in their quest for sustenance, are often seen fluttering gracefully among blossoms, sipping nectar from a variety of flowers, which plays a crucial role in pollination and ecosystem health. The Red Admiral's flight pattern is distinctive, erratic yet purposeful, allowing it to evade predators while foraging for food. One surprising trait of the New Zealand Red Admiral is its ability to adapt its behavior in response to environmental changes. During cooler months, these butterflies enter a state of diapause, effectively pausing their development until conditions are favorable. This remarkable adaptation not only ensures their survival during harsh weather but also highlights their intricate connection to the seasonal rhythms of New Zealand's ecosystems. As they emerge in spring, their vibrant presence signals the arrival of warmer days, creating a captivating spectacle for observers and a crucial link in the food web, as they serve as both pollinators and prey for various birds and other predators.

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