Madoryx bubastus is a moth of the family Sphingidae. It is found in Central America (including Costa Rica and Guatemala) and South America, including French Guiana and Venezuela south to at least Bolivia and Argentina. It is also present in Mexico. The wingspan is 92–120 mm. The upperside of the body and wings are olive-brown. There is a small, rounded or ovate, upper silver discal spot on the forewing upperside. Adults are probably on wing year round. The larvae have been recorded feeding on . Pupation takes place in a flimsy cocoon amongst leaf litter.