Theretra mansoni 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 India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

.

The length of the forewings is about 31 mm. It is very similar to Theretra alecto

Theretra alecto

Theretra alecto, known as the Levant Hawk Moth, is a moth of the Sphingidae family. It is found in the Indomalaya ecozone and warm parts of the Palearctic ecozone, including extreme south-eastern Europe.The wingspan is 75-106 mm....

and is probably no more than a melanic variation of this species. The difference between the two species is the ground colour of the upperside of the body and forewings and the undersides of both wings. This colour is dark brown in Theretra manilae, while it is beige in Theretra alecto.