The large yellow underwing (Noctua pronuba) is a moth, the type species for the family Noctuidae. It is an abundant species throughout the Palearctic realm, one of the most common and most familiar moths of the region. In some years the species is highly migratory with large numbers appearing suddenly in marginal parts of the range.

It is present in Europe, North Africa, Canary Islands, Middle East, Turkey, Iraq, Iran, Afghanistan, northwest India, Russia, Novosibirsk Oblast, Caucasus, Transcaucasia and Central Asia. It was introduced into North America at Nova Scotia. Since then it has increased its range considerably and has been recorded for Maine since 1985, and then spread throughout the northeast from Vermont and Massachusetts (1989) to New Hampshire (1990), New York, Maryland (1992), and Connecticut (1993). It was first recorded in Pennsylvania in 1998, North Carolina (1997) and west to Colorado (1999), Wyoming (2000), Washington (2000), California (2001), British Columbia (2002) and Alaska (2005).

This is a quite large and heavy moth with a wingspan of 50–60 mm (2.0–2.4 in). The forewings are quite variable from light brown to almost black. The darker individuals often have a pale streak along the costa. The hindwings are bright orange-yellow with a black sub-terminal band. As with other Noctua species (and numerous other insects), this contrast of bland-on-land and bright-in-flight is used to confuse potential predators. This species flies at night from July to September ^[1] and is attracted to light, sometimes in huge numbers. It will also visit flowers such as Buddleia, ragwort, and red valerian.

The larva is green or brown with two rows of black dashes along the back. This is one of the notorious "cutworms", causing fatal damage at the base of virtually any herbaceous plant (some examples listed below), sometimes severing it completely. This ubiquitous species is considered as a garden pest. The species overwinters as a larva and feeds on mild days throughout the winter.

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