Red Admiral

Red Admiral Vanessa atalanta (Linnaeus 1758)

Family: Nymphalidae, sub group Nymphalinae (The Nymphalids or the Vanessids)

Description

Photo above left and header photo by Martin Partridge

Photo above middle by Tim Furness

Photo above right by Martin Black

The Red Admiral is dark brown, almost black, with bright red stripes down the upper wings and red trailing edges on its lower wings. There are also bright white patches on the black wing tips and the upper wing colours look very crisp and distinctive. When the wings are closed the butterfly looks dark and mottled like a piece of bark. Females are usually larger than males.

The butterfly can fly at night, which is unusual, and sometimes gets caught in moth traps.

Habitat

This is a strong-flying migratory species which can turn up anywhere. Males defend territories, often in sheltered areas like gardens or woodland rides. The larval foodplant is mainly nettles and females often visit nettle sites, preferring strong growing nettles on well-manured or damp sites, or isolated clumps in sunny positions.

Adults also like places with lots of nectar, such as gardens, meadows and grasslands in summer, or places with rotting fruit, such as orchards or woodlands in autumn. The fruits can be apples, pears, plums, brambles, figs, tomatoes or others and they also feed on sap.

Distribution

The Red Admiral is a long-lived, annual immigrant from the Mediterranean region, which may sometimes try to winter in Britain and possibly in Yorkshire. Sightings can occur any month of year, but in Yorkshire mainly May to October or early November. Occasionally it can be seen as early as mid February. The numbers seen fluctuate a lot from year to year.

Within Yorkshire it can be found in most areas and at most heights, though it is found more in the south and south east of the county and less in the Dales.

Around the Mediterranean, it flies continuously through the winter months in suitable weather but can go into short-term hibernation for a week or two when cold and can probably pass winter in any stage. Yorkshire may receive several waves of arrivals, the earliest often from the Mediterranean or N Africa, followed later by a second generation born in France, central Europe or even southern England or Scandinavia.

In recent years overwintering appears to have been increasing, mainly in southern England, but larvae have been seen in winter diapause as far north as the Midlands and it’s possible some adults might hibernate in Yorkshire. However this has not been proved.

Outside of Britain the Red Admiral can be found from the Canary Islands up to Scandinavia and east across North Africa, plus Asia and North America.

Life Cycle

Females lay their small pale green eggs on the uppersides of young leaves of Common Nettle Urtica dioica and occasionally other related plant species. The eggs are laid singly and darken just before hatching, which is after one to five weeks depending on the weather.

Larvae are pale greenish-brown at first, turning to brown with black heads and occurring in pale and dark forms. Blackish spikes develop in the second instar. Larvae are parasitised by various wasps and flies and turn yellow if affected.

Larvae live in individual tents made by tying two leaves together with silk and the final tent is usually made by chewing part way through the top of the nettle stalk (about 15 cm down), causing it to flop over. The tent is pulled together with silk threads and the larva changes into a grey to pale brown pupa, blotched with varying amounts of gold. The pupal stage takes from two to four weeks.

There is still lots to learn about adult Red Admirals and how and when different generations breed and move north in the spring and how they survive winters. For example, despite arriving females appearing to be already mated, males set up temporary territories for a week or so at a time. However we have no evidence of courting or mating. Researchers don’t know if mating only happens at night, or high up in trees or not at all in Britain. From August to November Yorkshire Red Admirals head south, perhaps heading for the Mediterranean in winter. Do these adults breed when they get there and, if so, are these returnees important to the numbers? At Spurn point peak counts of hundreds of butterflies a day have sometimes been seen heading south in September.

Sometimes, instead of going south, Red Admirals try to hibernate, usually in the open, on the side of large trees in woodland, where they are almost impossible to see, or on sheds or houses.

Status

The species is not under threat.

Aberrations

It is rare to see most aberrations even though over 30 aberrations have been described. The exception is a variation with a small white spot in each of the red stripes, which is more often seen on females than males. Another variety, klemensiewiczi Schille, has a fuzzier pattern and orange stripes.

With thanks to The Butterflies of Yorkshire edited by Howard M Frost

Catherine Jones 09/02/21