Also known as the knapweed root-borer moth, these bright yellow moths are native to Eurasia but were introduced to the US in 1984 as a form of biocontrol in the fight against knapweed. They can now be found in most of the western states. Adults live for up to two weeks, with females laying up to 80 eggs on knapweed plants. The emerging larvae will bore into the roots of the plant, causing moderate damage.
Photo by Glenn Marangelo on 7/17/20 in Missoula, MT.