Acosmeryx sericeus is a moth of the family Sphingidae. It was described by Walker in 1856, and is known from Nepal, north-eastern India, Bangladesh, Thailand, southern China, Vietnam and Peninsular Malaysia.Wingspan: 96--106mm. Forewing with outer margin dentate. Forewing upperside general background colour violaceous-grey, with the brown lines more prominent than in other species of the genus; first discal line well-marked, running straight from vein M3 to the hind margin, merging anteriorly with an oblique line that reaches the outer margin just anterior to the hind angle; a grey submarginal band ends at or just beyond vein M3. Hindwing upperside with an indistinct brown discal line, distal to which is an equally indistinct, slightly tawny, paler band. Hindwing underside with conspicuous