Adhemarius gannascus is a moth of the family Sphingidae first described by Caspar Stoll in 1790.

It is known from Jamaica, Mexico, Belize, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Ecuador, Peru, Venezuela, Panama, Guyana, Suriname, French Guiana, Bolivia, Brazil, northern Argentina, southern Paraguay and Uruguay.

Adults are on wing year round.

The larvae have been recorded feeding on Ocotea veraguensis, Persea povedae, Persea americana and Damburneya salicina.

This Ambulycini-related article is a stub.