Lasionycta impingens is a moth of the family Noctuidae. It occurs from southern Yukon to Colorado.

It is diurnal. Adults are common in alpine tundra. It feeds on nectar of a Penstemon species on the Beartooth Plateau, Montana, as well as on Mertensia paniculata and a Senecio, likely Senecio lugens at Pink Mountain, British Columbia.

Adults are on wing in July and August.

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