The common name used here is of my invention. The larvae of this species rely on primroses for food. We have a bed of them each spring out in the crabgrass in the side yard, where I had dumped the plants that I tore out of a flower border in the front because they were invasive in the rich soil. In the side yard I don't mow the patch where they grow thickly until after they have bloomed in late May and early June. Our plants are pink and may be of the species Oenothera speciosa. The photo here is of a yellow Oenothera grandiflora or Grand Evening Primrose, by my friend Darryl Searcy who lepidopterizes and botanizes along the Escambia River in southern Alabama. He has a great website on Wildflowers, Butterflies & Moths of his region.