Tiny beetles hoped to clean up weed-clogged lakes

Thousands of water beetles about the size of a sesame seed are being released into Sudbury-area lakes to do battle with an invasive weed.

Known as weevils, the insects are meant to kill off Eurasian water milfoil, a slimy, green underwater weed that can grow as tall as the water is deep.

It’s the latest attack on the invasive weed, which found its way into Sudbury lakes about 30 years ago. The weed reportedly came to North America from Europe by attaching itself to ships.

So how can a tiny beetle choke out the leggy weed?

"What they do is they lay their eggs on the growing tips of the plants," said Kyle Borrowman, a manager working on the project.

"The eggs turn into larvae [and] these larvae burrow through the stem affecting the ability of the plant to grow."

The introduction of the weevils to combat the plant was approved by the city — along with the Sudbury Watershed alliance — last year.

By the end of next year, there will be 145,000 of the insects released into roughly six lakes. The project will cost the city $175,000 over the next three years.

The city's manager of environmental planning, Stephen Monet, said he expects the milfoil plant will be under control in two years, but noted residents still need to do their part to avoid introducing the plant into other lakes.

"We ask residents to be very cautious when they transfer a boat from one lake to another [and] to properly clean it with a pressure washer," Monet said.