Euclasta gigantalis is a species of moth in the family Crambidae. The female has a wingspan of 45mm.
It is found in Ethiopia, Kenya, La Réunion and Madagascar.
In 1988 this moth was also released in Australia for biological control of Cryptostegia grandiflora.
The larvae feed on Camptocarpus mauritianus, Cryptostegia grandiflora, Cryptostegia madagascariensis (Apocynaceae) and Clerodendrum heterophyllum (Lamiaceae).