Local Weevils to Serve as Biological Control

     Milfoil weevils, native to Wisconsin, are being raised by Amy Thorstenson and her team at the University of Wisconsin Stevens Point to control Eurasian watermilfoil. The weevils, who prefer the native variety of milfoil, can be taught to prefer the non-native by exposure and breeding habits.  "If an egg is laid on Eurasian water milfoil, the adult that hatches out of that will preferentially go back to Eurasian water milfoil to lay its eggs.  So eventually the generation shifts over to feeding on Eurasian water milfoil,” said Thorstenson.

     However, the weevils will not be a replacement for other management techniques, but hopefully another option; Thorstenson says it is difficult to collect the necessary numbers locally, and Wisconsin laws prevent her from ordering weevils from other states.