Ethmia helenmillerae is a moth in the Depressariidae family. It is found in Costa Rica, where it has been recorded from the Pacific slope of the Cordillera de Guanacaste at altitudes ranging from 0 to 579 meters. The habitat consists of dry forests. The length of the forewings is 6.3–6.8 mm for males and 6.5–7.5 mm for females. The ground color of the forewings is white with six defined dots distributed on two-thirds from the base. There is a line at the terminal area from almost the center of the wing to the tornum. The hindwing ground color is dark brown.