Parapoynx diminutalis is a species of moth of the Crambidae family. It is endemic to south-east Asia, including the Northern Territory, Queensland and New South Wales in Australia, but has since been found in the United Kingdom and the United States. It is also found in Africa, where it has been recorded from Egypt, Sudan, Ethiopia, Kenya, Uganda, Tanzania, Zambia, Zimbabwe, Malawi, South Africa, Botswana, Angola, the Republic of Congo, Nigeria and Madagascar. The larvae feed on Hydrilla and Nymphaea species.