Monday 30 October 2006

Painted lady

To stop this turning into a bird blog, here's another winged creature that's just as pretty but lacks a backbone—an Australian painted lady (Vanessa kershawi).

Species of painted ladies and the closely-related admirals (now there's the start of a music hall joke) are found worldwide. The Australian painted lady occurs in Australia and New Zealand. Specimens have even been recorded on Macquarie Island. It is partially migratory, moving south in early spring. Rather fewer individuals make the return flight north in autumn.

Caterpillars feed on a range of Asteraceae, including native Bracteantha and Leucochrysum, but their predilection for introduced species, especially Cape weed (Arctotheca and Scotch thistle (Onopordom), has allowed them to multiply. Museum Victoria's Bioinformatics database suggests that the species has increased in frequency over the past three decades.

This species has been mistaken for the more widely-distributed painted lady (V. cardui) and has been shifted in and out of synonymy with it. Vanessa cardui does occur in Australia but is now known to be restricted to the Perth – Bunbury region of the south-west. The WA population may have originated in Africa and become established in Australia following long-distance dispersal across the Indian Ocean. Like the Australian species, its caterpillars feed on a large range of host plants, so there will always be something for them to snack on.