Leucomonia is a genus of moths in the Sphingidae family, containing only one species, Leucomonia bethia, which is known from New South Wales and Queensland.Adults have grey forewings, each with some dark angular lines and a dark dot near the middle. The hindwings are dark brown.The larvae have been recorded feeding on Clerodendrum floribundum. Early instars are green with a forward-curving dark brown tail-horn.