“According to a study on monarch oviposition on swallow-worts by Casagrande and Dacey (2007), female monarchs will lay eggs on black swallow-wort even when it is in the same field as common milkweed. Laboratory tests have shown that monarch caterpillars cannot feed on black swallow-wort meaning swallow-worts act as dead-end hosts and those eggs are essentially wasted. As if that was not enough, black swallow-wort also comes with all the bad attributes and symptoms of most invasive species such as reduction of biological diversity, crowding out native milkweeds, invading open grasslands, and allelopathy. All of these affects [sic] hinder not only the monarch population, but the grass nesting birds, insect diversity, and the overall ecological integrity of any environment in which it exists. Luckily this problem is being recognized and actions are beginning to take place.”

The Central Upper Peninsula Cooperative Weed Management Area, with funding from Monarch Joint Venture, is studying treatment methods for black swallow-wort at Peninsula Point in the western Hiawatha National Forest. “The treatments being tested will be the mechanical pulling of swallow-wort and the use of prescribed burns. The Forest Service is planning to establish test plots where the effectiveness of treatment methods can be monitored and analyzed for effectiveness. This project will be important in protecting a sensitive monarch breeding and research site at Peninsula Point and provide a model for future control of these species in the crucial corn-belt breeding range for eastern North American monarchs” (MJV 2015).

• Monarch Joint Venture (MJV). 2015. Invasive Swallow-wort Assessment and Control at Peninsula Point. http://monarchjointventure.org/our-work/invasive-swallow-wort-assessment-and-control-at-peninsula-point.

Keywords: habitat, invasive species