Cataclysta lemnata, commonly known as the Small China-mark, is a species of moth belonging to the family Crambidae. It is a small insect with a wingspan of about 20-25 mm. The forewings of this moth are pale yellowish-brown with distinct dark brown markings, while the hindwings are whitish with a dark brown border. The larvae of Cataclysta lemnata feed on aquatic plants, particularly duckweed, and can be found near freshwater habitats such as ponds and marshes.