Black swallow-wort, Vincetoxicum nigrum (L.) Moench (= Cynanchum louiseae Kartesz & Gandhi), and pale swallow-wort, V. rossicum (Kleopow) Borhidi (= Cynanchum rossicum (Kleopow) Borhidi), are invasive plants belonging to the family Apocynaceae and are the targets of biological control efforts to