The species of Sesiidae reared from larvae feeding in the vines and tubers of sweet potato (Ipomoea batatas) in Kenya are described as new and named Synanthedon leptosceles and S. dasysceles, respectively. Illustrations are given of the adults and male and female genitalia of both species. S. leptosceles is differentiated from the superficially similar East African species S. erythromma Hmps., which also is associated with sweet potato. Aegeria pyrostoma Meyr. is synonymised under S. erythromma following the examination of type material. S. dasysceles is noted to be readily distinguishable from these and other known species of Synanthedon by the rough scaling and white markings of the legs.