Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Sweetfern Underwing (Catocala antinympha) is a moth of the Noctuidae family. It is found from Quebec and Ontario east to Nova Scotia and south to Connecticut, Rhode Island, New York, Massachusetts, Pennsylvania and Maryland.The wingspan is 45-55 mm. Adults are on wing from July to September. There is one generation per year. The larvae feed on Comptonia peregrina. A moth is an insect closely related to the butterfly, both being of the order Lepidoptera.