In southern Australia, the summer flying forms are usually pale yellow, with few or no brown markings on the wing undersides.

The winter forms are a brighter yellow, with pronounced brown markings on the wing undersides.

[5] Pupae are green, about 15 mm long, and attached to the host plant via a cremaster and central silken girdle.

During these migrations they fly in a steady, direct manner below head height, with the females being gravid and fertile.

[5] The females seem to prefer laying eggs on small plants growing in full sun.