Catocala junctura, the joined underwing or Stretch's underwing, is a moth in the family Erebidae. The species was first described by Francis Walker in 1858. It is found throughout temperate North America, ranging from New York and Pennsylvania west to Montana, Colorado, Oklahoma, Arizona, and into Texas, and north to southern Illinois, extreme southern Alberta and Saskatchewan; it has also been recorded west of the Rocky Mountains from California and south-eastern British Columbia. It is typically found near water, where the food plants of its caterpillar larvae grow plentifully.