Introducing the Beetles
by Mary Thill
Late-summer bloomers like goldenrod and asters are coming into fullness, as is the beautiful yet reviled purple loosestrife.
If you aren’t seeing much of the tall spiky wildflower at the edges of streams and wetlands these days, you may live in one of a growing number of communities releasing Galerucella, an Asian beetle that devours the invasive plant. So far, the insect seems to have an appetite for little else.
In Schroon Lake, bio control by beetle is a school project. The Mountainside Christian Academy students in the photograph below are displaying mesh enclosures they made to contain Galerucella beetles prior to release. Beetles were first set free at four loosestrife stands around Schroon Lake in 2008, according to Ellie Searles, a volunteer who mapped the plants and got the effort going.
“There has been a significant reduction in purple loosestrife in those areas where we had beetle releases,” Searles e-mailed this week.
There have also been beetle releases in Lake Pleasant, Lake Placid, Saranac Lake, the Champlain Valley and in Clinton County.
If you would like to learn more about how biological control of purple loosestrife works, the Adirondack Park Invasive Plant Program (APIPP) and Cornell Cooperative Extension are holding a workshop 2–4 p.m. Monday, August 20, at the Wild Center, in Tupper Lake. Follow this link for information and to RSVP.
APIPP summer educator Sarah Walsh said in an e-mail, “Beetles will not eliminate purple loosestrife, but they will control it. The issue with this plant is that it is such a prolific seeder that it produces plants faster than managers can really catch up with. Mechanical harvesting by pulling is tough and time-consuming, and using herbicide is tough too as purple loosestrife often is found in wet areas adjacent to wetland areas.”
The scientific literature of the past century is littered with examples of biological control gone wrong. In June this blog explored the parasitic wasp imported to North America to control gypsy moths; it continues to take a heavy toll on native moths and butterflies.
But Galerucella beetles seem to have a narrow appetite. They sometimes eat native loosestrifes if purple loosestrife is not available, so it is important to monitor their impact. But there seems to be consensus that the benefits of Galerucella outweigh potential risks. A Department of Environmental Conservation permit is required for their release in New York State.