The Migration of the Caper White.

So...today hundreds of white butterflies have been drifting past all heading in the same direction. They looked like Cabbage White Butterflies but it turns out they are called Caper Whites.The wildlife book we have says that the first stormy, hot weather of Summer coincides with migrations of adults which can persist for days.We drove into town and drifts of them were crossing the road and seemed to be heading north east.I have never seen anything like it before.The Australian Museum website says;"In spring many Caper White Butterflies migrate to where caper shrubs and creepers are more common. They usually fly inland, west of the Great Dividing Range. They maintain a rapid flight about 2 m - 3 m above the ground during the day, resting on shrubs and trees at night. Numbers in migrations can be very large. In some cases, the adult butterflies can clog car radiators, causing overheating.An interesting feature of this species is that it regularly migrates to areas where there are no food plants for its caterpillars. It is not understood why this behaviour has evolved."