Abstract
We present a genome assembly from an individual male Cosmia trapezina (dun-bar pinion; Arthropoda; Insecta; Lepidoptera; Noctuidae). The genome sequence is 825 megabases in span. The majority of the assembly (99.87%) is scaffolded into 32 chromosomal pseudomolecules with the Z chromosome assembled. The complete mitochondrial genome was also assembled and is 15.4 kilobases in length.