Large grey moth with long narrow wings and a darker grey wavy pattern. The abdomen has a dark line along the back. Males can make a hissing sound by rubbing scales over spines at the end of the abdomen. The caterpillars are green with diagonal white stripes and have a dark coloured horn on the end of their tail. Some caterpillars have purple brown markings along the back. Wingspan 12cm. The caterpillar grows to 8 cm.
Eastern and northern Australia.