Pediasia abnaki is a moth in the Crambidae family. It was described by Klots in 1942. It is found in North America, where it has been recorded from Maine, Michigan, Nova Scotia, Ohio, Alberta, Quebec, Ontario and New Brunswick. The habitat consists of grasslands. The wingspan is 20–28 mm. The forewings are greyish white with pale veins and scattered dark brown scales. The hindwings are greyish white. Adults have been recorded on wing from June to August. The larvae probably feed on the roots of grasses.