The attractive and unmistakable male Orange Tip butterfly (Anthocaris cardamines) is one of the first to emerge in the spring from its pupa (chrysalis). Within the pupa it has been metamorphosing from a caterpillar into a butterfly since June or July the previous year. Females emerge a week or so later, ensuring that there are enough males around to be able to mate within the few days the females are receptive.
In Britain this butterfly was once called “The Lady of the Woods” but the present English name of Orange Tip, while an accurate description, lacks the romance of the name the French (L’Auroré) or Germans (Aurorafalter) call it, both meaning “rising sun”. The butterflies can be found in suitable habitat throughout most of Europe, and eastwards across Asia as far as Japan.
The underwing patterns of both males and females are exquisite and unique among British butterflies. The female can sometimes be mistaken for a Small White or Green-veined White butterfly, until she closes her wings to reveal her tapestry underwing. The pattern performs, for both females and males, a useful camouflage function.
Males are usually on the wing from mid-April, though in a warm spring they can be seen in March. By early June they are almost gone, so we have just a few weeks in which to enjoy these delightful butterflies patrolling our hedgerows, tussocky meadows, parks and gardens in search of females to mate with. Females (who lack the characteristic orange wingtips) lie low, flying up only when a male appears. Because of its relentless visible patrolling, the male’s orange wingtips are thought to have evolved as a deterrent sign to bird predators, warning that the butterfly will be distasteful to eat. Its body contains bitter mustard oils absorbed from the food plant during the larval stage.
We have no March records in recent years on the reserve. Mid-April is our usual first record, with a latest sighting on 12th June 2013. The month of May is the peak flying season in Yorkshire. The past 30 years have seen a rapid increase in the range of these butterflies in the British Isles, particularly Scotland and Ireland, probably in response to climate change. For possibly the same reason, the flight period now occurs significantly earlier in Britain than when the UK Butterfly Monitoring Scheme began in 1976.
Once mated, the females find suitable plants on which to lay their eggs, usually just one to a plant. Once the female has laid an egg on the plant, she leaves a pheromone which deters other females from laying there. The usual food plants for the Orange Tip are Cuckoo Flower (or Lady’s Smock) Cardamine pratensis and Garlic Mustard Alliaria petiolata (also known as Jack-by-the-Hedge). There is normally not enough edible material to sustain more than one caterpillar per plant so the larvae are cannibalistic, eating other eggs or larvae on ‘their’ plant.
Young larvae start by consuming the flower petals and end up eating the developing seed pods before it is time to pupate. Both the main plant species mentioned above are found on the reserve at St Nicholas Fields, but while Cuckoo Flower is rather scarce and mostly seen in the meadow areas, Garlic Mustard is abundant along the pathsides and in woodland glades. In our gardens they are attracted to Honesty Lunaria annua and Dame’s Violet Hesperis matronalis among other flowering plants mostly of the Brassica family.
When, after 5 or 6 changes of skin, the larva has completed its growth, it pupates by climbing onto a nearby woody stem, attaching the characteristic pointed boomerang-shaped pupa by a girdle around the stem. The story has come full circle, and if the pupa is not predated or otherwise damaged, the butterfly will be ready to emerge the following spring to delight us once more.
All photos were taken at St Nicks except for the header photo (Wiki Commons license).