''Psyche casta'' is a nocturnal moth from the family Psychidae, the bagworm moths. The wingspan of the males ranges from 12 to 15 millimeters. The females do not have wings. The host plants are from the groups: Poaceae, birch, willow, poplar and ''Vaccinium''. The caterpillars make a protective hull from grass. The flight time ranges from May to July.