Eupatorium adenophorum Spreng is a strongly invasive plant originally from Mexico but now a globally-widespread malignant weed. E. adenophorum may have spread globally when free of its natural enemy constraints (such as competitors, pathogens and predators). It releases inhibitors which interfere with the development of other species [9, 10]. In recent years, an increasing number of studies have shown that the terpenes in E. adenophorum comprise a class of important inhibitors which have allelopathic activity, antioxidant activity, antimicrobial activity, acaricidal activity, nematode activity as well as activity against other pests [11, 12–17]. However, there are no known reports of the ability of E. adenophorum oil extracts to control P. myriotylum.