Mylothris rubricosta, the eastern swamp dotted border or streaked dotted border, is a butterfly in the family Pieridae. It is found in Sudan, Ethiopia, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Tanzania, Malawi, Zambia, Mozambique, Botswana and Zimbabwe. The habitat consists of papyrus swamps.
Adults have a weak flight and stay close to the ground. Adults feed on the flower nectar of Persicaria barbata. They are on wing from August to March.
The larvae feed on Persicaria barbata species.