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Weevils help park fight invasive weed

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Since Friday morning, 12,000 new bugs now call Perch Lake home.

A bunch of bugs may not sound like a good thing to some water lovers. But to Perch Lake lakeshore property owners and Homestead Parklands officials, an expanding population of milfoil weevils is welcome news.

The hope is that more bugs will mean fewer weeds in the lake.

Officials with the Citizen Science Center at Beaver Creek Reserve and Golden Sands Resource & Development Council, along with local volunteers, spent several hours at the lake on Friday transplanting the bugs from coolers into the chilly lake water.

According to Jeanette Kelly, Citizen Science director with Beaver Creek Reserve, the Perch Lake weevil project is in the second year of a two-year grant. Last year the first 12,000 weevils were placed in the lake. This year that number was duplicated.

Over the past decade, Perch Lake has seen an increase in the growth of Eurasian watermilfoil, an invasive weed that chokes out native aquatic plants and can hamper swimmers and boaters.

To combat the spread of the weed, volunteer divers at first attempted to pull the milfoil up from its roots, but the weeds quickly grew back.

There are chemical treatments for Eurasian watermilfoil, but Kelly said Perch Lake boosters wanted to switch to natural, biological methods to eliminate the expanding weed mats.

Enter the milfoil weevil, which are found naturally in Perch Lake but not in sufficient numbers to effectively control the current Eurasian milfoil outbreak.

Thanks to the Wisconsin Department of Natural Resources' Aquatic Invasive Species grant program, Perch Lake was targeted for the rearing and introduction of a large population of milfoil weevils.

"This is a more environmentally-friendly solution," Kelly said of the weevils. "And, in the long run, it's a cheaper solution."

Now that the weevils have taken up residence in the milfoil weed beds near Perch Lake's shoreline, the hope is that the small bugs will do what comes naturally. The weevils love to eat milfoil and have proven to be an effective control method for the weeds.

From this year forward, Kelly said, the weevils will be left to reproduce naturally and attack the milfoil in Perch Lake.

Kelly said she will be completing a weevil survey in the coming months to see how the small creatures are faring in Perch Lake. While she has no firm data yet, Kelly said she has a sense that the project is accomplishing its intended goal.

"The weevils have been doing what we want them to do," she said. "I will say, in general, that we've seen significant weevil damage in the milfoil beds we've examined."

Now that the Perch Lake project is coming to a close, Kelly said Beaver Creek Reserve hopes to work with other lake associations across Wisconsin to boost weevil populations in order to control the spread of Eurasian watermilfoil.

She said the organization will also continue to be involved in educational programs, like the state's "Clean Boats, Clean Waters" campaign, which encourage boaters to be aware of invasive aquatic plants and to not transfer such species from one body of water to another.