Vanessa cardui originates from North Africa and is also a resident in the Canary Islands, Madeira and some Mediterranean regions; migrating in large numbers with the help of the African wind currents. The species covers most of Europe and has also been recorded in Iceland, Greenland and Svalbard.
The mated female has a multiple choice of host plants, to lay her eggs. The eggs are about the size of a pin head and are pale green in colour, which are laid on the underside of the host plants leaves.
The hatched larvae become caterpillars for the next ten to twelve days, feeding on the host plant leaves. The caterpillar will form a silk tent for it to hide from predators, this tent acts as a camouflage for the larvae, unfortunately this tent is vulnerable to many predators so a high number will be killed before pupating. It takes about ten days from being a chrysalis to becoming a butterfly, in this time it is mainly defenceless; this being the most vulnerable time in a butterfly’s life.
Soon after becoming an adult butterfly, they will mate and complete the life cycle.
In the hot dry summer months of Spain, the species is almost absent from lowland areas in Catalonia until late in August and into September. Moderate numbers are recorded as part of the autumn migration (Throughout the winter months Vanessa cardui cannot survive the cold regions of Europe) and small-scale breeding does occur here, before they eventually head back towards the African regions.
Although some of these late‐summer butterflies may be able to survive the winter, in the southern Spanish regions, virtually all the locally produced population flies southward to Africa, as shown by the sudden appearances of huge numbers of V. cardui in the Maghreb, the Canary Islands and the northern edge of the Sahel.
