Both caterpillars and adults of this species eat eucalyptus leaves. See also the photo of eucalyptus leaf beetle caterpillars, probably a different species from the adult shown above.
Classification
from Australian Faunal Directory
Order Coleoptera - Beetles, 24955 named species in Australia
Family Chrysomelidae - leaf beetles, about 2455 named species in Australia
Subfamily Chrysomelinae - 700 named species in Australia
Genus Paropsisterna - 122 named species in Australia
Species Paropsisterna nr laesa
Note: Identification made by Martin Lagerwey, who provided the following comment: "I have determined at least four species in the Paropsisterna laesa complex, three undescribed and unnamed. There is likely to be more. Your species is not possible to determine without dissection. It is possible that we will refer simply to the laesa complex for practicality."