THE EFFECTS OF PURPLE LOOSESTRIFE BIOLOGICAL CONTROL BEETLES (GALERUCELLA SPP.) 
ON PURPLE LOOSESTRIFE PLOTS ON THE UPPER MISSISSIPPI RIVER NATIONAL WILDLIFE AND 
FISH REFUGE.

Lara Hill
U.S. Fish and Wildlife Service, Upper Mississippi River National Wildlife and 
Fish Refuge, Onalaska, WI 54650.

Purple loosestrife (Lythrum salicaria) is an invasive exotic plant in North 
American wetlands.  It displaces native vegetation, forms dense monocultural 
stands, and eliminates natural food and cover plants essential to many wildlife 
species.  Purple loosestrife is a large aggressive plant with deep roots that 
produces millions of seeds each year.  It spans across 26 states and an 
estimated 400,000 acres, making control by herbicides, hand pulling, mechanical 
manipulation, burning, and water manipulations ineffective and infeasible.  In 
1994, the U.S. Department of Agriculture approved the release of two biological 
control insects for purple loosestrife. Researchers discovered the insects in 
the plant's native range of Europe and demonstrated that the insects were safe 
and effective in reducing purple loosestrife.  The leaf and stem-eating beetle 
Galerucella spp. has been released on six sites of the Upper Mississippi River 
National Wildlife and Fish Refuge - La Crosse District (Refuge).  The root-
eating weevil Hylobius tanversoviattauus, has been released on 2 sites.  In 
addition, two Galerucella spp. field insectary sites were created on Trempeleau 
National Wildlife Refuge. Many factors contribute to the success of the beetles 
in reducing purple loosestrife. Monitoring has shown a decrease in plant 
densities and vigor at several of the sites.  

Keywords: purple loosestrife, biological control, galerucella spp.