Weevils no match for invaders: Eurasian milfoil still chokes Sudbury lakes

Despite a three-year, $175,000 project, Eurasian water milfoil still remains in 18 Sudbury lakes.

In 2011, the city introduced tiny water beetles, known as weevils, into six local lakes.

The insect was introduced to eat away at the invasive species that squeezes out other plants, makes swimming and boating difficult, and generally clogs up lakes.

Stephen Monet, the manager of environmental planning initiatives at the city, said the goal was never the complete elimination of the invading plant.

"When you`re using biological control agents like the milfoil weevil on a target organism like Eurasian Water Milfoil, the aim is not to eradicate," he said. "That would be nice but it doesn`t remove that plant completely from a lake. What it does is it can control its population."

The weevils had one job: knock the milfoil out

Monet said the weevils' role was to knock the milfoil over so native aquatic plants could regenerate.

That didn't happen in the Sudbury lakes because the native plants did not survive.

The result? Eighteen lakes still have milfoil, and likely more to come. 

Monet conceded that the program wasn't "as successful as people were anticipating."

"Perhaps there was some expectation that there would be a much further decrease in a much more rapid timeframe, for the action to happen," he said.

Waiting game to see if lakes can heal themselves

The weevils didn't completely eliminate the milfoil, so now it's a waiting game to see if the lakes can return themselves to health.

"It's almost a race, if you will, as to which lake can recover the fastest in terms of the biology of the lake," Monet said.

"All of our lakes are recovering, many from much farther than others, meaning they were in a poorer state than some other lakes."

Monet says the city is now focusing on educating boaters on identifying and removing any invasive species when going from lake to lake.

But that's not a lot of encouragement to those lake-dwellers where milfoil is a big problem.

Lake residents have had enough milfoil

Carole Young, who lives on McFarlane Lake, said that residents have taken matters into their own hands. 

"They cut it so they can walk into the water without being impeded by the milfoil," Young said. "When you're boating in the channel your motor gets plugged with the milfoil. Often you'll have to clean the rudders."

The six lakes where the weevils were introduced were: Richard Lake, Long Lake, McFarlane Lake, St Charles Lake, Simon Lake; all had Eurasian Milfoil.

It's believed Eurasian Water Milfoil was introduced first in McFarlane Lake where a floatplane station was in the 1950s. The milfoil was found where the airplanes were 'parked'.