Isognathus excelsior is a moth of the Sphingidae family. It is known from Colombia, Venezuela and Ecuador to north-western Brazil.It can be distinguished from all other Isognathus species by the pure white underside to the abdomen with conspicuous paired black spots on each segment.There are probably multiple generations per year.The larvae probably feed on Apocynaceae species. They have long tails and are very colourful, suggesting they are unpalatable to birds.