We present a genome assembly from an individual Limnephilus marmoratus (a caddisfly; Arthropoda; Insecta; Trichoptera; Limnephilidae). The genome sequence is 1,630 megabases in span. Most of the assembly (99.93\%) is scaffolded into 30 chromosomal pseudomolecules, including the assembled Z sex chromosome. The mitochondrial genome has also been assembled and is 15.4 kilobases in length.