Their head is smooth and their body is covered with dark, plumose setae (feathery hairs).

The whole life span of this moths is about 41 days, producing up to nine generation in a year under laboratory conditions.

The larvae of this moths feed on fireweed (Senecio madagascariensis an Asteraceae), a plant also native to Madagascar that has been introduced to Australia and Hawaii, where it has become an invasive pest.

[2] To a lesser extent they also feed on Delairea odorata, Senecio vulgaris, Crassocephalum crepidioides, Emilia fosbergii, Erechtites hieracifolia and Helianthus annuus (sunflowers).

[3] In December 2012 the United States Department of Agriculture approved the release of Galtara extensa in Hawaii to combat the spread of fireweed.