Eurema daira, the fairy yellow, barred yellow or barred sulphur, is a butterfly of the family Pieridae.

It is found from Argentina north to the southern United States.

Strays can be found up to southern Arizona, South Dakota, southern Texas and even Washington, D.C.

Adults are on wing year round in the southern part of the range and in late summer and fall as vagrant.

Adults feed on the nectar of various flowers including joint vetches and shepherd's needle, and are the principal pollinators of Cnidoscolus urens.