Here Come the Ladies

Painted Lady, Vanessa cardui

The influx of Painted Ladies has begun. The Painted Lady butterfly (Vanessa cardui) has started arriving in Ireland, an annual migration that brings variable numbers of this large, buff-orange butterfly, not only here but to much of Europe. The butterflies travel from Africa, generally believed to be north of the Sahara in areas around Morocco (1). Recent meteorological trajectory analyses of migrants however have shown that the range may even extend further south into the Sahel zone south of the Sahara (2). By thus migrating, V. cardui avoids the harsh African summers, making use of the plentiful supply of its favoured larval food Creeping and Spear Thistles. A second influx arrives in August and September of second generation migrants from Southern Europe. No life stage of V. cardui can survive the Irish winter and adults will return south, however this is rarely observed as it is believed to occur at very high altitudes (3). Orientation upon such migration is believed to be maintained by the use of a sun compass in flight (3).

References:

1. Nash et al., 2012. Ireland's Butterflies, A Review pp. 165-167
2. Stefanescu et al., 2007. Journal of Animal Ecology 76 pp. 888-898
3. Nesbit et al., 2009. Animal Behaviour 78 pp. 1119-1125