The map butterfly is very unusual indeed.
For many reasons, the Map (Araschnia levana) is a very special butterfly. It was first seen in South Limburg in 1939. By the early sixties, it was found throughout the southern half of the Netherlands, and in 1983 it reached the West Frisian Islands of Texel and Terschelling. Since then, it is a butterfly that you can find in the entire country.
Another unusual fact about the map butterfly is that it looks very different in the spring and the summer. So different, in fact, that Carolus Linnaeus cataloged them as two different species in 1758. The spring map as Papilio levana and the summer form as Papilio prorsa.
When butterflies appear different from one season to the next, they call that seasonal dimorphism. This is caused by the length of the days and temperature during the caterpillar and pupae stages.
The first generation in the spring is red-orange with black spots, while the summer generation is black with a white band, and looks like a miniature white admiral. On the underside of the wings is a complex pattern of colored spots and stripes, It looks a bit like a map, and this is where this butterfly gets its name.
Also interesting is the way the females lay their eggs in long strings, one on top of the other. on the underside of stinging nettles, the larval food source.It is thought that they resemble the nettle flowers, confusing predators. These string vary from 5 to sometimes 20 eggs long. Each female will lay an average of 67 eggs at a time, and will lay 3 or 4 times. That nearly 200 eggs total.
The map usually flies in two generations, but if warm weather persists, can sometimes produce a third generation. Then you’ll see map butterflies flying until the middle of October. The markings of this third generation is sometimes a combination of the the spring and summer generations. The map will hibernate over the winter as pupae.
Above: The spring generation, the underside of the wing, and the summer generation.
Left: Eggs, caterpillar, and pupae.