A woman with a wide smile standing in a farm field with her husband

Getting into the weevils

By Isaac Burke | July 30, 2018

Montague, Massachusetts

The weevils almost died.

En route to the drop sites on a warm June day, the delivery truck carrying them was sent on a longer route—almost too long.

There was little time to spare before the tiny insects overheated in the back of the truck. The biologists frantically called the delivery company to track down and guide the vehicle to the release site.

It arrived just in time to save the weevils.

If this seems like an odd amount of fuss for some poppy seed-sized black bugs, it kind of is.

But in the last few years, weevils have become one of the best lines of defense against Polygonum perfoliatum, better known as the mile-a-minute vine. It’s an apt nickname: the a creeping, prickly perennial invasive plant has quickly wedged its way into landscapes all along the Eastern Seaboard. From forests to stream sides, roadsides to open fields, the plant’s telltale triangular leaves have taken over many areas with its rapid growth, starving the native plants underneath it of sunlight.

In western Massachusetts, mile-a-minute has always been largely concentrated around one spot, which today is occupied by Red Fire Farm in Montague. An organic vegetable farm owned and operated by local couple Ryan and Sarah Voiland since 2007, the land was once owned by a nursery, which left behind huge numbers of mile-a-minute plants and seeds. The plant has been a nuisance on their land, and has spread to to several other sites in the Connecticut River watershed.

“We didn’t know what it was at first—that was one that we hadn’t seen before,” Sarah Voiland said. “It’s kind of spooky seeing it grow over everything.”

The farm has had mile-a-minute for as long as the Voilands can remember. It’s less of a problem for them in areas where they till or clear the land, but it is a nuisance in their strawberry fields, and along the edges of the property. It also seems to like hedgerows, and finds plenty of space there to thrive and spread its seeds.

“Once it’s outside the realm of people keeping it in check, it’ll just scramble over every sunny area,” said Cynthia Boettner, Invasive Plant Control Initiative Coordinator for the U.S. Fish and Wildlife Service's Silvio O. Conte National Wildlife Refuge. “The most important goal is to keep this species from spreading.”

In trying to control the plant, wildlife conservationists are lending a helping hand in the local food industry. Led by Boettner, and her counterparts from the Massachusetts Department of Agricultural Resources and the state’s Division of Fisheries and Wildlife, the Service has been pulling and weed-whacking mile-a-minute on and around the property since 2014.

“It’s been four to five years of us wringing our hands, wondering what to do about it, so I’m really grateful they’ve got the plan and resources to do that,” Ryan Voiland said. “Realistically, we can’t pay to remove it all, so it’s a big help.”

The pulling and weed-whacking set back some of the vine’s growth over the last couple of years, but this year is the first time in western Massachusetts that weevils have been used on the invasive. Since Red Fire is an organic farm, growing many different types of vegetables and berries to be sold locally, spraying herbicides there is not an option as it had been on other sites.

“Part of what we’re trying to do as an organic farm is protect the wildlife by not spraying chemicals and reducing nutrient runoff,” said Sarah Voiland. “Partnering with the state to get rid of these invasives is something we’re glad to do.”

Winning with weevils

The weevils traveled all the way to Montague from a lab in New Jersey, which supplies many mile-a-minute control programs on the East Coast. They arrived in several small containers that looked like they might contain KFC mashed potatoes.

Two biologists holding small, styrofoam container full of tiny insects.
Weevils cling to the inside of their container and need to be shaken out. Photo by Isaac Burke, USFWS.

Those in attendance carefully removed the containers’ lids and then shook them out above a concentrated patch of mile-a-minute. One could almost imagine the plant letting out a small shiver as a ball of weevils, each one tinier than a pencil tip, tumbled onto the plant’s leaves.

Mile-a-minute has been a growing problem in the eastern U.S. since the 1930s, when the vine, native to eastern nations including Japan, Russia and India, was first detected there. Since then the plant has grown largely unchecked, blanketing entire areas in spiny green stems. It wasn’t until the early 2000s that weevils were first discovered as a potential solution to the mile-a-minute problem. In 2004, a University of Delaware study concluded that weevils were an effective biological control for the invasive vine.

Two biologists release another group of weevils amongst the invasive vines
Releasing the weevils above another patch of mile a minute. Photo by Isaac Burke, USFWS.

Since then, numerous states have had a great deal of success reversing the plant’s growth with the little insects. Weevils not only eat the vine, but they also lay their eggs on it. When the eggs hatch, the larvae burrow into the host plant. They then must then eat their way out, often killing or disrupting the vine before it has the chance to go to seed.

But the best part? This breed of weevils won’t eat anything other than mile-a-minute. According to Boettner, the species is so specific in its diet that it will virtually never take a bite out of another plant. This means that if biologists can find the invasive, then they can drop the weevils on it and walk away without having to worry about affecting native plants. The weevils become almost like tiny drones, programmed to seek and destroy exactly one thing.

Tiny tic-like insects spread out across a green vine
Weevils begin making their way down onto a mile-a-minute vine’s leaves. Photo by Isaac Burke, USFWS.

“We need to do everything we can to control this pest, and weevils can find places we can’t,” said Sarah Grubin, acting state survey coordinator for the Massachusetts Department of Agricultural Resources (MDAR). “The weevils are a permanent, long-term solution.”

Weevils have had their struggles in Massachusetts, though. While they have been an effective method of control farther south, weevils have had a limited impact in the eastern part of the state, where they have been used since 2010. There could be several reasons for this, including the longer winters of New England. Progress fighting the invasive back has been slow - perhaps too slow, as the plant’s seeds are viable for up to seven years and can continue to be spread through bird droppings.

Hands holding a damaged mile-a-minute-vine.
As the weevils eat the vine, they cause damage and discoloration before eventually killing the plant. Photo by Isaac Burke, USFWS.

And yet, some progress is better than none.

“We have at least one site where no mile-a-minute plants have been observed in fruit for seven years,” said Karro Frost, conservation botanist for the Massachusetts Division of Fish and Wildlife. “I still check the area at least two or three times a year to be sure there are no plants and haven’t seen any for a couple of years now. So we have had some successes.”

Botanists and farmers agree that the public can help, too. The best defense against mile-a-minute is knowing where the vine is popping up.

“If more of the public would get involved, we could easily take care of problems like this,” said Sarah Voiland.

For now, the team at Red Fire Farm waits with bated breath. Will the weevils win?

If you think you might have mile-a-minute on your property, or have seen it elsewhere, please help us control it by learning to identify it and reporting it here:

Isaac Burke is a science communications writer for the Northeast Regional Office in Hadley, Massachusetts.

The U.S. Fish and Wildlife Service supported this Nature’s Good Neighbor through our Partners for Fish and Wildlife Program, a voluntary initiative that works with private landowners to improve fish and wildlife habitat on their land. A phone call or email is all it takes to learn more with one of our 250 private lands biologists. If you are interested in improving habitat for fish and wildlife on your land, please find your local Partners for Fish and Wildlife biologist.