Milfoil Home Page

Welcome to the Milfoil Home Page, containing links to information and treatment options for milfoil and other lake pests. Recently updated for 2001!

Eurasian watermilfoil, or Myriophyllum Spicatum L. is becoming an increasing problem in the freshwater lakes of North America. Luckily, research and experience are discovering ways to cope with the problem.

Links to information on milfoil

Overview of Milfoil History and Treatment

One of the best milfoil articles on the Internet is the report Technical Information about Myriophyllum spicatum (Eurasian Watermilfoil) from the Washington State Noxious Weed Control Board. It includes a description of milfoil and its growth patterns, a history of its introduction to North America, treatment methods, and a bibliography. The same source also offers a less technical overview, General Information about Eurasian Watermilfoil.

Center for Aquatic Plants

The University of Florida hosts this extensive collection of information and illustrations covering a variety of water plants, including European milfoil. This site is being added to regularly and it would be worthwhile to spend time exploring here. Some of the milfoil-related links include the following:

The University of Florida also sells several educational videos for the modest price of $15 each. Relevant titles include:

  • What Makes a Quality Lake?
  • Emersed Plants Part I (Aquatic and Wetland Plant Identification Series)
  • Emersed Plants Part II (Aquatic and Wetland Plant Identification Series)

(I think Emersed Plants Part II is the one which covers milfoil.)

Washington State Department of Ecology

The Washington State Department of Ecology has some very helpful information on milfoil control, including the following:


I've experienced herbicides first-hand when fluridone was used to treat the lake I live on in Washington State. Our small (150 acre) lake was heavily infested with milfoil and herbicide treatment was deemed the best option by the lake committee.

Maybe it was, but it was sad just the same. Many native plant species died off, and a water reed which survived took advantage of the opportunity to become a minor pest itself. Though fish were not immediately impacted, the loss of habitat had a devastating impact on fish populations in the following years. Two years later, surveys tell us that the milfoil has not returned, but the water maintains a strange, dead quality (looking flat and dark even when the sky is blue). I haven't seen a fish in months.

The Minnesota Department of Natural Resources web site recommends using only spot applications of herbicides and states:

...application of fluridone to whole lakes or bays causes high levels of unavoidable damage to native vegetation and has the potential to affect other aspects of lake ecosystems...

Based on my experience, it is worth exploring alternative methods of control before reaching for the chemicals. They're expensive, have no guarantee of long-term results, and if used widely are likely to adversely impact lake health.

Other Milfoil Info

The University of Wisconsin oversees the Wisconsin Lakes Partnership. They offer online publications like their Lake Classification factsheets and recruit and train volunteers who monitor local lakes in order to catch milfoil infestations early.

Minnesota Pollution Control Agency has published an excellent non-technical introduction to Milfoil. A 12 minute video, Stop Exotics, Clean your Boat, is available from Minnesota DNR (cost $10).

The New Hampshire Exotic Aquatic Species Program has published a concise and useful chart of Plant Management Techniques.

Did you know there are forms of milfoil native to North America, which are not a threat like the non-native variety? The Tri-Lakes Association of Sherburne County, Minnesota USA has published information to help you identify native vs. non-native milfoil.

Another good overview is offered by the Wisconsin Department of Natural Resources.

Luke's Report on Milfoil originated as a school report but contains a lot of information.

Biological Controls

One of the more intriguing biological control possibilities is the milfoil weevil, or Euhrychiopsis lecontei. An employee from the Washington State Department of Ecology told me that these weevils occur naturally in many northwest lakes and love to eat European milfoil. Early attempts to introduce the weevil into new lakes were disappointing but ongoing research is learning how to increase their effectiveness. Here are links to internet sites with information on the weevil.

Another possible biological control is the moth of the water caterpillar Acentria Niveus. This article reports that the milfoil biomass in New York's Lake Cayuga was reduced by 90%, possibly because this non-native moth likes to nest in floating milfoil blossoms.

Scientific Papers and Reports

For the scientifically inclined, there have been many studies on growth habits and treatment methods for aquatic plant pests.

Candlewood Lake, Connecticut

A newspaper article explains how the 15-year infestation at Candlewood Lake in Connecticut is being managed by a technique of lowering the lake level during the winter to expose the milfoil to freezing temperatures.

Maintaining Water Quality

Beyond the milfoil issue is the question of how we can maintain and improve the water quality of our fresh water lakes. The following articles may be helpful.

Recommended Reading

Lakescaping for Wildlife &
Water Quality
, by Carrol L. Henderson, Carolyn Dindorf, Fred Rozumalski

If you own a lakefront home, you'll enjoy the many graphics and easy style of this book. Nine chapters deal with lakeshore landscaping and problems, site preparation and plant installation, shoreline stabilization and maintenance, good stewardship and more. Appendices help you identify native plants and invasive non-native plants.

Buy the book from

Earth Ponds Sourcebook:
The Pond Owner's Manual and Resource Guide
by Tim Matson

Tim Matson offers practical advice and resources to help you build and/or maintain a healthy pond, including symptoms of a dying pond and ideas about how to prevent, or reverse, the aging process.