Once established, biological controls can be self- maintaining, reducing the need for repeated treatments. The weevil lays its eggs on the tips of the milfoil plant. When the young hatch, they burrow down the stem, eating their way through the plant and slowing plant growth or shearing the top of the plant below the water surface. The weevil occurs in Minnesota, Wisconsin, and Illinois, and was discovered in northern Indiana at Saugany Lake, Laporte County, in 1997. Methods Waters selected for demonstration should have an obvious infestation of Eurasian water milfoil with reason to believe that if the milfoil were controlled, native plant diversity would rebound.
Weevils are apparently more successful if raised in the same region as the target lake.
A supplier in Ohio cultures and markets weevils under the trade name MiddFoil . Due to possible regional variations, weevil treatment in two northern Indiana natural lakes could be compared with treatment of a southern reservoir. The lakes have similar characteristics for use as experimental comparisons. Herbicide use will have to be restricted in conjunction with the weevil treatment, so residents would need to be willing to put up with unpredictable lake conditions during the testing period. Lakes where watershed contributions to weed growth have been controlled will probably have more success using in-lake treatments.