The Facts . . .On

EurasianWater-Milfoil

locate a weevil, look in milfoil stemsfor signs of damage. There are oftensmall holes or weak spots in thestems that point to weevil damage.These holes allow water to enter thestem, expose the plant to bacterialinfection and decrease the plant’sbuoyancy. The plant will drop lowerinto the water column and will notcanopy out on the surface. Overtime, weevils can impact thepopulations of EWM, but completeeradication is unlikely. Additionalresearch and development is neededbefore biological control withweevils can be considered aneffective management tool.

How Can You Help?EWM is moved between waterbodies by small fragments trans-ported on recreational equipment.Commonly it is transported byboats, trailers, bait buckets, livewells and fishing equipment. Tohelp prevent the spread of EWMand other invasive species, pleasetake the following steps:

Inspect and remove any visiblemud, plants, fish or animalsbefore transporting.

Drain water from equipment(boat, motor, trailer, live wells)before transporting.

Dispose of unwanted live baitin the trash.

Wisconsin laws prohibitlaunching a boat or placing atrailer or boat equipment innavigable waters if it has aquaticplants or zebra mussels attached.

PUB-WT-781 2004 PRINTED ON RECYCLEDPAPER

How Do You Control EWM?Early detection ofEWM growth iscritical instopping the plantfrom becoming awidespreadproblem. The bestchance to haltthese non-nativeinvaders is whenthey first appearon the scene.EWM often appears near boatlandings and at disturbed sites.

New colonies are best removed beforethey expand. Hand pulling andremoval from the water is a simpleand effective control method for smallareas. Harvesting, raking orscreening the bottom also works well.Milfoil can be effectively treated withselected chemicals early in thesummer before plants flower. A permitis required from the DNR for chemicaltreatment or bottom screening.Whole-lake herbicide treatment isnot generally permitted because of thepotential to disrupt lake ecosystems byeliminating both invasive andbeneficial native plants.

For lakes dominated with beds ofmilfoil, control efforts must be focusedon reducing its spread. Mechanicalharvesting can open areas for boatingand swimming and cut fish cruisinglanes. Harvesting encourages growth ofnative plants while removing milfoilcanopies that limit native plant growth.

Biological control of EWM is stilluncertain. A small aquatic weevil(Euhrychiopsis lecontei) feeds on milfoiland actually prefers EWM. Weevils arefound in many Wisconsin lakes. To

The Clean Boats,Clean Waters ProgramBuilds Awareness About

Learn to recognize EWM.

Start a volunteer watercraftinspection program to helpeducate boaters on how andwhere EWM and other invasivesare most likely to hitch a rideinto water bodies.

Begin monitoring boat landings,marinas and inlets for the firstsign of invasion.

If you suspect a new infestation,report it to your local DNRservice center.

Remember, our waterways are thepride of Wisconsin and belong toall of us.

For more informationabout the “Clean Boats,Clean Waters” programcall 715/346-3366.

The Wisconsin Department of Natural Resources providesequal opportunity in its employment, programs, services,and functions under an Affirmative Action Plan. If youhave any questions, please write to Equal OpportunityOffice, Department of Interior, Washington, D.C. 20240.

This publication is available in alternative format (largeprint, Braille, audiotape, etc.) upon request. Please call608/267-7694 for more information.

Aquatic Weevil(Euhrychiopsislecontei)

Designed by L. Pohlod, Blue Sky Illustration & Design, LLC

It is important to be able to distinguishEWM from similar aquatic plants.

EWM is a submersed aquatic plantwith feather-like leaves arrangedin whorls (circles) on the stem.

There are usually 12 to 21 pairs ofleaflets per leaf.

The leaves have a distinct feather-like appearance, with the lowerleaflet pairs about half the lengthof the midrib.

Stem tips are tassel-like.

Branching is abundantin water 3 to 10 feet deep.

Eurasian water-milfoil(Myriophyllum spicatum)

What is Eurasian Water-Milfoil (EWM)?Invasive species disrupt the stabilityof natural ecosystems and threatenbiodiversity. One invasive species ofspecial concern is Eurasian water-milfoil. EWM was introduced intoNorth America and has spread tonumerous water bodies across thenation. During the 1960’s thisaggressive submersed plant found itsway into Wisconsin waters. For acurrent list of EWM-infested waterbodies visit www.dnr.wi.gov/org/water/wm/GLWSP/exotics/milfoil.html

Eurasian water-milfoil threatensnative aquatic plant communitiesand forms thick underwater beds oftangled stems and vast mats ofvegetation at the water’s surface.These dense beds cause loss of plantdiversity, degrade water quality, andmay reduce habitat for fish, inverte-brates and wildlife. They also hinderboating, swimming and fishing.Many lake organizations and localgovernments devote much of theirmanagement budgets to control thisinvasive plant. EWM is an afflictionthat costs citizens of Wisconsinmillions of dollars in plant controland lost tourism revenue annually.

How DoesIt Spread?This prolificplant does notspread well byseeds. It spreadsby shoots andrunners thatcreep along thebeds of lakesand rivers.New plantsalso growfrom smallfragmentstransported from one water body toanother. Commonly it’s transported byboats and trailers but could also betransported on SCUBA gear, water skisor waterfowl. EWM has become asuccessful invader primarily by meansof its stem fragments. A singlefragment can take root and form anew colony.

EWM is most successful in waterdisturbed by cultural developmentssuch as shoreline construction,watershed runoff, aquatic invasivespecies control or heavy boat traffic.

EWM also has a competitiveadvantage in waters that are stressedby pollution. It has difficulty becomingestablished in waters with healthypopulations of native plants. Ahealthy ecosystem and preservation ofnative plants is protection against anEWM invasion.

Northern water-milfoil(Myriophyllum sibericum)

What Does Eurasian Water-Milfoil(Myriophyllum spicatum) Look Like?

EWM is one of eight water-milfoilspecies found in Wisconsin and theonly one that is not native. The mostcommon native water-milfoil in Wis-consin lakes is northern water-milfoil(Myriophyllum sibericum). It bears astrong resemblance to EWM but it is notprone to the rapid growth and canopyformation that make EWM a nuisance.