Adult monarch butterflies, Danaus plexippus, sometimes visit dry or injured parts of certain plants to take up toxic chemicals called pyrrolizidine alkaloids. They do this by regurgitating saliva onto the surface of the plant to dissolve the chemicals, creating a solution that they then suck up using their proboscides. These alkaloids do not provide the butterflies with food or energy. Despite being very poorly documented, this behavior potentially plays one or more important roles in the life history of Danaus plexippus. Better understanding of this curious aspect of their biology could also contribute to successful conservation. More information is provided under Resources.