Hunt is on statewide for wetland invader
Purple loosestrife is pushing out native plants
By DON BEHM
Milwaukee Journal Sentinel staff
State residents are searching more than a dozen counties
this month for infestations of an aggressive European
invader - purple loosestrife - that is shoving aside native
wetland plants and the animals that depend on them in
a steady march across Wisconsin.
In canoes, boats and cars, on foot and bicycles, about
150 volunteers for the Wisconsin Wetlands Association
are noting the locations of the tall, magenta spires of
loosestrife in Milwaukee, Ozaukee, Racine and other counties
along the shores of Lakes Michigan and Superior.
Information gathered by this surveillance squad will
help the association and other groups target future loosestrife
control efforts in those counties, said Derek Strohl,
the association's program director.
"We hope to take the survey statewide next year because
that has not been done in 15 years," Strohl said. The
search is funded by grants from the Wisconsin Coastal
Management Program and the American Transmission Co.,
whose employees frequently encounter the weed.
Since the last statewide census of this exotic nuisance
was done in 1987, purple loosestrife has spread across
Wisconsin and is now found in marshes, wet meadows, lake
shorelines and roadside ditches in each county, said Brock
Woods, an aquatic ecologist and coordinator of the University
of Wisconsin Extension's purple loosestrife biological
At least 40,000 acres of wetlands have been overrun by
this seemingly indestructible plant.
"The La Crosse River is choked with loosestrife," Woods
said. "New London is the color purple along the Wolf River,
and the Wisconsin River at Stevens Point is purple." So,
too, is the City of Superior.
Wherever loosestrife goes, most other life departs.
"We lose the diversity of plant and animal life in our
wetlands," Woods said. "You won't find our native insects
in loosestrife, so birds and spiders that prey on the
insects also leave. As loosestrife knocks out cattails,
it also knocks out muskrats that depend on them. And the
dense stands of loosestrife also eliminate fish spawning
Purple loosestrife gains the upper hand in competition
with native plants for two reasons: its height and its
uncommon ability to produce seeds.
"This loosestrife out-competes any other wetland plant,
including cattails, sedges and bulrushes," Woods said.
"It can get to be 8 to 9 feet tall and shades out the
A single stalk produces 100,000 seeds or more each year,
and mature plants grow as many as 50 shoots. As loosestrife
matures, it forms dense root clumps that push aside everything
This alien was first found growing wild in Wisconsin
in the early 1930s but did not gain a foothold in wetlands
of major rivers and their tributaries until the 1970s.
Beginning in the 1800s, purple loosestrife was imported
from Europe and sold as a showy garden perennial. Horticulturists
promoted its attractive blooms. Then it began to spread
from gardens to wetlands.
Today, it is illegal to distribute the plant in Wisconsin
and 23 other states.
The absence of natural predators on this continent allowed
purple loosestrife to advance across the United States,
according to Woods.
Subsequently, researchers turned to its homeland to find
something that would slow its growth.
Galerucella beetles were imported from Europe in the
early 1990s for only one purpose: eating purple loosestrife
leaves. They do not eat our native wetland plants, and
it is a lot easier for citizens to release beetles than
it is to pull or cut loosestrife, Woods said.
Since 1997, the state Department of Natural Resources
has distributed beetles to conservation clubs, lake associations,
schools, Boy Scout groups and farmers. More than 300 groups
and individuals have reared large colonies, eventually
releasing several million beetles in the last five years
to combat the loosestrife invasion.
"Evidence of beetle success is stunning in places, such
as Henrietta Lake in Waukesha County, while other areas
have been slower to show changes," Woods said. "The bad
news is that there is still a lot of loosestrife out there
To fill the gaps, the University of Wisconsin Cooperative
Extension Service will schedule several workshops this
fall to train more citizens in the rearing and release
of the beetles.
Jay Sadlon, a member of the Buttes des Morts Conservation
Club, has helped release about 200,000 beetles since 1999.
These little predators wiped out about 80% of the loosestrife
in one wetland near the mouth of the Fox River in Lake
Butte des Morts where the club is attempting to restore
wild rice and bring back ducks and other wildlife, Sadlon
"The beetles don't get rid of it, but they do control
it," he said.
Loosestrife, however, still dominates 300 to 400 acres
of wetlands in the lake, according to Sadlon.
The Lake Poygan Sportsmen's Club released a few hundred
thousand beetles late last month in a wetland on the north
shore of that lake, said Gordon Alfter, a club member.
Millions more will be needed to chew up all the loosestrife
on the shores of Lake Poygan, according to Alfter.
"There's miles and miles of marsh here that we've already
lost to purple loosestrife," he said.