Farm overtaken by Parthenium weed P. hysterophorus near Emerald, Central Queensland, Australia. Parthenium is a declared plant introduced from Mexico and the USA which has overrun and degraded thousands of hectares of grazing land in north and central Queensland. It grows rapidly, is easily spread and causes severe dermatitis and hay fever. Several biological control agents have been released in an attempt to control its spread: stem boring, stem galling & leaf mining moths, seed eating, stem boring and stem galling weevils, a leaf eating beetle and a rust.