Eurema mexicana, the Mexican yellow, sometimes called the wolf-face sulphur,[2] is a North and South American butterfly in the family Pieridae.

It occurs mainly in Mexico but occasionally is found in central and southwestern United States and rarely in Canada.

[3] The upperside of the wings is pale yellow with a black forewing submarginal border outlining a "dog" or "wolf-face" pattern.

Boisduval's yellow is smaller and brighter yellow, the male has a weaker "dog face" pattern, the female has reduced black on the upper side, and the hindwing is less sharply pointed.

[2][5][6] This butterfly may be seen almost all year in Arizona and Texas, and April to November in New Mexico.