I always wanted to write about Painted Lady migrations. Everyone knows that birds leaves cold north Europe for search of warmer places. Learning about butterfly migrations is usually a surprise. One or two inquisited people would then mention famous monarch (Danaus plexippus), which flies every year from Mexico to Canada, more than two thousands kilometers. Almost nobody knows that here in Europe, at the place we live, we can watch a butterfly which is able to travel 3-4 thousands kilometers between continents.
Painted Lady (Vanessa cardui) belonging to Nymphalidae family, is not Polish or even exclusive European butterfly. It is one of the most commonly spread insects over the globe. I think that only in rainforests it cannot be found. Everyone who is even remotely interested in little colorful flyers certainly knows it. But only researchers - lepidopterologists are aware, that great part of its short live it spends on travel which could be a challenge even for birds skilled in sky journeys.
Painted ladies migrate every year. It is a part of their life cycle. Every year they hatch from eggs in North Africa on the edge of desert, when spring arrives and the weather for a short time becomes calmer, like european summer, and from time to time even rains. Soon it becomes too warm and dry, so the butterflies leaves to the north. Usually they fly alone and in dispersed groups, and it is no easy way to track them. There are however times when painted ladies imagos are hatching from pupae almost simultanously and en masse they begin flight to Europe, visible on radars. Such spectacular migrations can be observed from time to time - usually every few to dozen years - but most favourable conditions for seeing them are within south Europe, when all the butterflies still fly together.
Painted ladies use almost the same ways as storks. I mean these butterflies that arrive to Europe (so in Poland too) in the late spring. After leaving the pupa, the butterfly begin its journey almost immediately, and after few tens of hours (if the winds are favourable) they are on the second coast of Mediterranean Sea. There, still like stork paths, their migration paths splits to various countries. These starting from Morocco fly over Spain and Portugal. These from Egypt fly through eastern Europe. All the rest fly over Alps at the height of several thousands meters, arriving at Austria, Germany and France, usually as two migration waves between late April and mid-June.
And where the butterflies arriving to Poland become from? They could be from anywhere. From Morocco, Tunisia, Algier, Libia or Egypt. In opposite to bird migration paths, Painted Ladies again join their paths flying to the north, and again fly together over Baltic Sea.
Which way they return? The answer is surprisingly short: I don't know. Nor do I, nor does anyone else. Despite many attempts nobody was able to establish their routes. We only know that between late September and October, in Maghreb countries extremely exhausted from long flight painted ladies suddenly show up, only to give life to another generation which will leave Africa next year. But no scientist ever observed that return flight over Europe. Maybe they fly at so high altitude that cannot be observed; maybe their route is completly different, and for example leads over ocean? Nobody knows.
And some people say that everything is already discovered and explored...
