Isognathus australis is a moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

 of the Sphingidae

Sphingidae

Sphingidae is a family of moths , commonly known as hawk moths, sphinx moths and hornworms, that includes about 1,200 species . It is best represented in the tropics but there are species in every region . They are moderate to large in size and are distinguished among moths for their rapid,...

 family. It is known from north-eastern Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

.

The wingspan

Wingspan

The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...

 is 70 mm for males. It is similar to Isognathus rimosa rimosa and Isognathus rimosa papayae but has narrower wings. The forewing upperside is unicolorous brown, shaded with white, except for a yellow band along the posterior margin and the faint traces of a distal marginal band. The basal area of the hindwing underside is yellow, the rest is brown with a bluish tinge, becoming black towards the anal angle.

There are probably multiple generations per year. Adults have been recorded in January.

The larvae have been recorded feeding on Plumeria

Plumeria

Plumeria is a genus of flowering plants of the family that includes Dogbane: the Apocynaceae. It contains 7-8 species of mainly deciduous shrubs and small trees...

species. Pupation takes place in cocoons spun amongst leaf litter.