The Caper White Butterfly migration is on again!

Every 6 to 10 years, South East Queensland and Brisbane have a huge influx of Caper White butterflies. They migrate east, over the Great Dividing Range looking for food plant to lay their eggs.

There is no simple answer as to why this happens. It could be that conditions are right to produce so many butterflies that they must migrate to find food plant for their caterpillars.

Source:
http://www.brisbanetimes.com.au/queensland/millions-of-butterflies-flutter-through-southeast-queensland-skies-20161105-gsiryu.html 
http://toowoombaplants2008.blogspot.com.au/2010/12/butterfly-host-plants-for-toowoomba.html