Butterfly migration in the Canary Islands - Why so many in autumn?

If you're visiting the Canary Islands in autumn, you may be a witness to a really interesting event, unique for this time of the year: the migration of the Vanessa cardui butterfly from the north of Europe to warmer climates.

You often see news articles about this phenomenon or posts from people wondering what is happening and why there are so many butterflies suddenly on the islands.

The Vanessa cardui is one of the most widespread of all butterflies and in spring they migrate from North Africa and the Mediterranean to Britain and Europe.

Scientists have been wondering for a long time if in autumn these butterflies migrate back to warmer climates, as it was hard to observe them since they tend to fly at really high altitudes.

It seems that sometimes they make their way back to the African continent and on their way they stop in the Canary Islands, where they can be observed in late September or in October. 

It takes a series of stops and up to six successive generations to reach their final destinations, as one butterfly can't usually fly for more than 1700 km in his lifespan and in total they travel for 14,500 km (9,000 mi) round trip from tropical Africa to the Arctic Circle.

Several experts have said that the presence of these butterflies in the Canary Islands greatly favors the environment, especially after all the vegetation fires which have occurred during summer in Gran Canaria and other parts of the archipelago. These butterflies feed on weeds so they can "help" clean the burned areas.

Also, they do not affect local species of butterflies like the 'Monarch' because they are only passing through, so there's no need to worry.

Have you seen these butterflies in parks and garden areas around Tenerife, Gran Canaria, Lanzarote Fuerteventura and the rest of the Canaries?