Saturday, December 28, 2013

The geranium bronze

Geranium bronze, Cacyreus marshalli,
The geranium bronze is a recent addition to the butterflies of the Maltese islands. It is native to South Africa where it feeds on wild pelargonium geraniums (sardinell in Maltese) which also originate in South Africa. This species is often is often considered a pest because of the damage it causes to the cultivated pelargonium.
The South African butterfly was first recorded in the Balearic Islands in about 1987. It was feeding on cultivated pelargonium geraniums. From there it was introduced to Spain, France and Portugal. In 1997 it arrived in the UK. In Malta it was recorded for the first time in spring 2007.
Once it arrived in Europe it spread quickly in Mediterranean countries mainly because of the popularity of its food plant as well as because parts of South Africa have a Mediterranean climate. It thus found the right conditions to survive and expand its range.
At present it is restricted mainly to Mediterranean Europe but its range might expand further north as is happening with other species. Studies have shown that as a result of global warming and climate change, the range of several species of butterflies is moving north. At the same time some species are disappearing from their former range as the climate becomes too warm for them.
As butterflies disappear in one area new species appear in areas where they had not been recorded before. It is assumed that this is also happening with other insects such as moths, flies and bees, which are not as easy to record and monitor as butterflies.
On continental land masses this is a continuous process but on islands such as Malta insects might disappear because of these changes but new ones are added more slowly as potential invaders might find it difficult to cross the sea separating the Maltese islands from North Africa. 

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