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Olivia is another medium-size (approx. 3.5 cm. wingspan) grey-brown western aridland Euxoa, variable in appearance and difficult to characterize except by genitalic characters. In the male, the forewing ground is yellow-brown to orange-brown and the hindwing is white shading to brown along the margin. Females are grey or silver grey on the forewing with a pale grey hindwing with darker veins. Olivia belongs to the Euxoa subgenus Heteroeuxoa; males can be identified by the asymmetrical saccular extensions and the shape of the vesica, and females by the shape of the bursa from which the ductus seminalis arises. Although the female of olivia has a corpus bursa similar to that of the E. ochrogaster species group, the ductus seminalis arises ventrolateral to the ductus bursae instead of dorsal or dorsolateral. In the male genitalia the harpe is c-shaped, markedly curved in the apical half, and the sub-basal diverticulum is lacking and replaced by a spiny pouch of vesica. Lafontaine (1987) provides illustrations of the adults and genitalia of olivia, as well as keys to the subgenera and species of Euxoa.