Swallowwort is an invasive weed native to Europe that has spread widely across North America. It is also known as Vincetoxicum and Cynanchum. Other common synonyms for swallowwort include dog-strangling vine, devil's shoestring, and black swallowwort. These names come from the plant's ability to choke out other vegetation and the vine-like, twisting nature of its growth. The leaves and stems of swallowwort are toxic to many animals, but insects like monarch butterflies have evolved to use the plant as a host for their eggs and caterpillars. Efforts are underway to control and eradicate swallowwort in many areas where it has become a problem for native plant and animal species.