The cabbage white butterfly, Pieris rapae, is an invasive species that long ago established in North America. Likewise, Garlic Mustard, Alliaria petiolata, is an invasive plant that displaces native North American wild flowers in forests and understory shaded areas. Garlic mustard and cabbage are both protected by glucosinolates that caterpillars of cabbage white butterflies can metabolize. Garlic mustard has few herbivores and is not heavily damaged by cabbage white caterpillars compared to the damage caused to cabbage. A recent report finds that cabbage whites do colonize and successfully develop on garlic mustard however, their use is infrequent. Adult preferences for sunlit open areas over forested, shaded areas may limit the use of garlic mustard.
Sam L. Davis1 and Don Cipollini. Evidence for Use of Alliaria petiolata in North America by the European Cabbage White Butterfly, Pieris rapae. Psyche. Volume 2016, Article ID 9671506,