Archive for the ‘Weevils’ Category

More on Weevils

Tuesday, December 11th, 2007

Adult Weevil (Euhrychiopsis lecontei)This page is intended as a resource for us and for others that want better to understand how weevils might help Lake Fairlee bring its rampant milfoil infestation under control. It will include links to other pages that (purport to) know more than we do.

Cornell University has one of the best starting points for understanding this miniscule herbivore. LINK The resource contains a clear explanation of the economic and ecological damage that milfoil can cause and some photos of the little beetle that might offer a less invasive and more permanent way of bringing it under control. LINK The University of Minnesota has a good summary of weevil research. LINK Wisoconsin’s DNR published this concise paragraph:

Eurhychiopsis lecontei, an herbivorous weevil native to North America, has been found to feed on Eurasian water milfoil. Adult weevils feed on the stems and leaves, and females lay their eggs on the apical meristem (top-growing tip); larvae bore into stems and cause extensive damage to plant tissue before pupating and emerging from the stem. Three generations of weevils hatch each summer, with females laying up to two eggs per day. It is believed that these insects are causing substantial decline in some milfoil populations. Because this weevil prefers Eurasian water milfoil, other native aquatic plant species, including northern watermilfoil, are not at risk from the weevil’s introduction. LINK

Other states have been exploring the use of weevils to control milfoil.

Vermont’s official position is that weevil treatment of milfoil is experimental. They will license it but not fund it. LINK Fairfield Pond in the northwest corner of our state has been introducing weevils for three years Middlebury College 2005 and this year declared the program a success. Middlebury College 2007 We remain cautiously optimistic.

The Vermont effort is led by Dr. Sallie Sheldon of Middlebury. She has been studying and promoting the milfoil weevil for 15 years. She has partnered with a company called EnviroScience which is developing weevil introduction commercially and marketing it as the MiddFoil® process. LINK

It is your author’s belief that any long term resolution of the milfoil problem will include an ecological balance. Mechanical (or chemical) means are temporary at best. Possibly these milfoil weevils can help us get there sooner. On the other hand, the history of biological interventions is fraught with unintended consequences.

Considering Alternative Strategies: Weevils and Herbicides

Tuesday, September 18th, 2007

Besides hand picking, suction harvesting, bottom barriers, and benign neglect, there are two noteworthy ways of dealing with milfoil infestation that have been tried recently in nearby lakes.

TriclopyrThis summer our sister lake received permission to begin using the herbicide triclopyr to kill milfoil in their lake. The applications will continue over the next few years, and traditional harvesting measures have to continue. Nonetheless some Lake Morey residents are already declaring the experiment a success.

Beginning in Fairfield Pond2005 tiny herbivorous insects were introduced into Fairfield Pond (near St. Albans) to eat the milfoil growing there. They are Euhrychiopsis lecontei, commonly known as milfoil weevils, which are a native insects that normally feed on native Northern milfoil plants. Fairfield residents are happy with the results to date.

As a result your Lake Fairlee Association board members have been asked with increasing frequency whether and when we will be undertaking one or the other of these tactics. This blog entry is my attempt to answer those questions.

First some general observations. Our association was formed to preserve and enhance the natural beauty of Lake Fairlee. Our bias is in favor of keeping the lake “natural.” We are well aware of the “law of unintended consequences” which frequently plagues those who attempt to combat one outside invading species by introducing something else. And we are cautious, not likely to try anything that has not been tried and proven elsewhere.

weevil adultBoth chemical treatments and weevils are relatively new, at least in Vermont. We are somewhat skeptical of the glowing early reports, as they come from those who are invested in each “solution.” It is only natural that well meaning lake associations, once they have decided to adopt a program, tend to focus on the beneficial aspects.

On the other hand, we understand that our milfoil problem will not go away. No amount of suction harvesting and bottom barriers will remove all the milfoil from our lake once and for all. renovate otf bag Indeed, if it magically happened that one day all the milfoil were gone, it would likely be just a matter of time before milfoil would be reintroduced and begin to spread again. I liken milfoil to crabgrass or mosquitoes. They must be contended with but we cannot expect ever to be finally rid of them.

Therefore we are glad for the experiments of other lakes. We will watch their progress and study their results. The State of Vermont is also studying and evaluating these strategies, as their permission is required for chemical or weevil treatment (as well as for suction harvesting and bottom barriers). For the time being we will continue to harvest milfoil and to slow its spread with bottom barriers, which are effective and necessary, but not final.

Following are some links to more information about milfoil eating weevils and the herbicide used in Lake Morey. (more…)