form a gray to pale blue-green chrysalis. There is a thin longitudinal yellow stripe and a thin red line along the back of the chrysalis. Adults Adult males are most active before mid-morning, when they can be seen flying along hedges. At the hottest part of the day, they are typically found flying at the tops of trees. Migration Statira sulphur are notable for their large annual migrations in the tropical areas of the Americas between May and July. They fly upriver in the dry season and downriver toward the ocean in the dry season. In the Amazon, as they fly north, they cross the river to settle on the moist sands of the Upper Amazon. Populations will also cross the ocean to inhabit nearby islands like the Antilles. There are many accounts on the impressiveness of statira sulphur migration, when the butterflies can be seen flying in very large groups. Evolutionarily, migration poses an increased risk of death during the move. Thus, the benefit of moving to a new location must outweigh the risks of migration. To facilitate migration, statira sulphur have evolved several mechanisms to ensure they fly to the correct destination. Much research has been done on the statira sulphur for its ability to adjust its direction of migration under windy conditions. A study conducted in Panama demonstrated that Aphrissa statira loses its navigational capacity when exposed to a strong magnetic field, suggesting it uses the Earth's magnetic field to navigate. When experimentally exposed to strong magnetic fields, their orientation of migration was more dispersed. When experimentally exposed to a reversed magnetic field, the butterflies tended to orient themselves for migration in the opposite direction as they normally would. Together these findings demonstrate that the species uses the earth's magnetic field to help orient their migration. This is consistent with several species of migratory birds which also use the earth's magnetic field to differentiate the direction of the equator and the poles. Additionally, in their migration, statira sulphur are also influenced by the direction of the sun and by the presence of landmarks. Conservation References Coliadinae Butterflies of North America Butterflies of Central America Butterflies of the Caribbean Pieridae of South America Butterflies of Cuba Lepidoptera of Brazil Lepidoptera of Colombia Lepidoptera of Ecuador Lepidoptera of Venezuela Fauna of the Amazon Taxa named by Pieter Cramer Butterflies described in 1777