Immature stages of Xestia brunneopicta (Matsumura, 1925) are described and illustrated from an ex ovo rearing. The female was collected during a Finnish-Russian expedition to the province of Chita in East Siberia in 2013. Eggs were laid in a plastic jar at Chara Sands on the 7th of July. Larvae hatched between the 20th and 21st of July. Rearing of larvae was undertaken in Finland by four lepidopterologists. A key is given that includes the known European larvae of the subgenus Pachnobia Guenée, 1852 sensu Lafontaine et al. (1998), mostly based on the morphology and larval chaetotaxy. The closest relatives on the basis of larval morphology are discussed.