More on Weevils

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.