Seasonal dimorphism – what is that?
Photos: Arne Ader
Translation: Liis
Representative of the autumn generation of map butterflies
Map butterfly Nõgeseliblikas Araschnia levana
The phenomenon with one species having differently looking imagos at different times of the year is called seasonal dimorphism.
Representatives of the second or so-called autumn generation of map butterflies can be encountered flittering around already in early July. The main colour of the wings is black, with a white segmented band. The lower edge of the hind wings have a white fringe, above that a narrow orange band. So the representatives of the autumn generation (Araschnia levana f. Porsa) look.
The wing shape of map butterflies seems more angular, wing span 4-4,5 centimetres, and so their measurements remain up to a centimetre smaller than those of the quite similar white admirals.
Map butterfly
The underside of the wings have an arresting, rather complex network of white veins. Chestnut brown main colour, with a broad white band in the centre.
Map butterfly (spring generation)
For comparison and as a reminder a photo of the spring generation imago. We meet them already in early May, during about a month. At that time the map butterflies have wings with light brown, dark-spotted upper sides (Araschnia levana f. Levana). For both generations of butterflies neither the wing shape nor the intricate pattern of the wing undersides change significantly.
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