Weevils Hard at Work Behind North Haven Village Hall

One of several tiny mile-a-minute weevils munching away at the leaves of a mile-a-minute vine behind North Haven’s village hall. Five hundred were released there last spring. Peter Boody photo

Five hundred new residents of North Haven are thriving in the brush behind village hall, chewing holes in an invasive weed that has been taking over woods and borders all over the region, including the brushy woods of the village.

They have Asian roots but they’re American born, raised in an insect lab by the New Jersey State Department of Agriculture, which sells them. They arrived last spring in a container not unlike a 7-Eleven coffee cup, packed inside a big a shipping box with dry ice.

“It was very high tech,” joked Village Clerk Eileen Tuohy, who said they cost the village of North Haven $1 each. The tiny bugs were released by Building Inspector George Butts and then-Village Clerk Ed Deyermond and left to fend for themselves in the patches of phragmites and brush along the fringes of North Haven’s Stock Farm nature preserve.

They are mile-a-minute weevils, a species introduced from Asia to the United State in 2004 after much study of the potential consequences. Their sole purpose in life here in the U.S. has been to eat the one thing they like to eat: mile-a-minute weed, a fast-growing invasive vine with thorny stems and triangular waxy leaves, also from Asia, that is taking over the Northeast like a Yankee version of kudzu, another Asian transplant running rampant in the Southeast U.S.

The village has no protocol for measuring the success of their biocontrol effort but a casual inspection on Monday turned up several weevils munching away. There were lots of the characteristic “buckshot” holes in the tangled mile-a-minute vine leaves that indicate the weevils are doing their job.

North Haven resident Susan Edwards is the one who first suggested using weevils to suppress the weed. Ms. Edwards is regular observer at village board meetings, a member of North Haven’s Board of Architectural Review & Historic Preservation and a recently re-elected director of the John Jermain Memorial Library.

She was traveling last week but confirmed by email that she “did mention this to the village several years ago.” She wrote that Trustee John Saskas brought the idea up at a board meeting “much more recently.” He did not return phone calls for comment.

Mayor Jeff Sander remembers Ms. Edwards as the prime force behind the idea. “We did it and I hope it works,” he said on Monday. He noted that mile-a-minute weed reseeds itself relentlessly and returns as an annual in the spring. Of the 500 weevils munching away behind village hall, he said, “I’m not sure they will do any good.”

“Looks like you have a good establishment” of weevils, commented Andrew Frederick Senesac, a Ph.D. specialist in weed science for Cornell Cooperative Extension Suffolk County, after seeing a photo of North Haven’s weevils at work on a mile-a-minute vine on Monday.

He wrote in an email that he was involved in releasing the MAM (mile-a-minute vine Persicaria perfoliata) weevils (Rhinoncomimus latipes) at four sites in 2018. Three were on the North Fork. “I was not involved with a release in North Haven, nor was I contacted by anyone there. This is the first I have heard of it,” he wrote.

“I just finished an end-of-the-season evaluation of the weevils’ level of establishment and damage to the nearby MAM vines,” he added. “Because we had to release in late July this year, the best we could hope for is the weevil population got established well enough to survive the upcoming winter.

“In my travels this year, I have observed the typical ‘buckshot’ holes in most the MAM that I saw. This is diagnostic for evidence of the presence of the weevil. In the past few years, I have seen slight to moderate damage at many infestation sites. This is likely due to weevils that have made their way to Long Island from surrounding states that are also releasing them.”

The damage he’s seen was not “heavy enough to do much more than slow the weed a little,” he wrote. “The purpose of the releases is to increase these ‘background’ populations to the point where they are self-sustaining and can actually cause suppression of the weed. This is a long-term project and goal. I am hoping that we see better results in the next few years.”

Mile-a-minute weed thrives in areas where there is partial shade but can survive in full sun. It is often found on the edges of homeowner properties near woods and sometimes on the periphery of field nurseries.

At this time of year, the vines produce shiny black seeds contained in clusters of fleshy blue berries. The fruit are very easily knocked off the vine and are spread by migrating birds and other wildlife, according to an article Dr. Senesac wrote for the Cooperative Extension.

Because the ripened fruit are so easily dislodged, vines should not be hand pulled after fruit begin to form in late July. Recent research has shown that even immature green fruits can eventually mature off the vine to produce viable seeds for re-infestation, Dr. Senesac wrote.

It was Dr. Judy Hough-Goldstein at the University of Delaware who in 2004 identified the small Asian weevil as an effective biocontrol. On eastern Long Island, the weevil has been evaluated with controlled releases since 2012, according to Dr. Senesac.

If North Haven’s weevils survive the winter, he wrote, they will begin to feed on the leaves early in the spring and continue all season. Eggs are laid in the stem and the larvae weaken the stem as they develop and begin to feed.

“Unfortunately, there is a lot more weed than weevil, so we will continue to try to increase the weevil population,” Dr. Senesac wrote.