What natural enemies are approved for use against purple loosestrife?
Three species of plant feeding beetles, Galerucella calmariensis, Galerucella pusilla and Hylobius transversovittatus show the greatest promise as biological controls for purple loosestrife. The Galerucella leaf beetles feed on bud, leaf and stem tissue causing defoliation and prevention of flowering/seed production. Continued defoliation leads to plant death. Hylobius is a weevil whose larvae mine in root tissue weakening and ultimately killing the plant. These insects have undergone extensive testing to determine their safety and effectiveness, receiving USDA approval in 1992. At the request of the Michigan Department of Natural Resources (MDNR), the Michigan Department of Agriculture reviewed and approved the release of these insects. The MDNR’s releases of Galerucella in 1994 have established well and are beginning to show impacts. The result of 1996 releases of Hylobius are still uncertain.
