During the period of 1976-1983 migratory fluxes of two species of Pieridae butterflies were observed in Brasília, D.F., Brazil. These flights presented regular annual periodicity and constant direction. In the spring great concentrations of Phoebis (Aphrissa) statira were flying southeast against the wind. During summer Anteos clorinde was observed flying against the wind In the opposite direction (SW). These migrations are probably related to longitudinal gradients of host plants fenology.