Greenwich (AP) - Scientists are encouraged that tiny beetles unleashed last year in northwest Greenwich are beginning to make a dent in the spread of an invasive plant species.

"We are seeing good establishment of the weevils," said Donna Ellis, co-chairwoman of the Connecticut Invasive Plant Working Group. "They made it through the winter just fine and they are dispersing all over."

In 2009, 7,000 weevils were brought to Connecticut for the first time, 2,000 of them released in the 80-acre Gimbel Sanctuary, a nature preserve maintained by Audubon Greenwich. The insects immediately went to work last summer nibbling away on the leaves of the mile-a-minute vine, an invasive species that has spread throughout the eastern United States.

"The leaves look like Swiss cheese," Ellis said.

There is also some evidence of the insects' larvae in the vine's stems. That's the most effective means of control since the larvae consume and interrupt the flow of nutrients and water along the vine's stem. In some cases, the damage inflicted by the larvae may also kill the plant by causing the stem to topple, Ellis said.

The vine is believed to have arrived in the country in a delivery of holly seeds from Japan to a now-defunct nursery outside of York, Pa., in the 1930s.

Lacking a natural predator, the vine, which lives for one year, can grow as much as six inches on a hot summer day. It wraps around and grows over other plants, drastically reducing sunlight to the plants and hindering their growth.

Scientists were seeking a natural means to control the spread of mile-a-minute instead of using chemical methods. Tests done in China and the United States determined that the weevil, no longer than an eighth of an inch, would help control the spread of the vine without attacking other native plant species, Ellis said.

The vine was first spotted in northwest Greenwich in 2000. Many of the plants took root in Gimbel Sanctuary.

The vines have spread north by several thousand feet, said Alexandra Moch, an environmental analyst with the town of Greenwich.

"We see small patches spread in a line," she said. "Even with that, we are happy with the results we have seen so far."

But in a remarkable development, weevils have been spotted in a couple of those new patches about three-quarters of a mile from the original site, said Ellis.

"That shows the weevils are searching for the vines and moving away from the original site," she said.

In July 2004, the weevils were first released in White Clay Creek Park, in northwestern Delaware close to the Pennsylvania state line, and helped reduce the mile-a-minute population there, Ellis said.

In addition to the 7,000 weevils released in Connecticut in 2009, another 6,000 have been released this year, with 4,000 of those released in Stamford on May 21, she said.

Ellis said there's a slight possibility more weevils will be released in Greenwich in August.

But the weevils are in high demand as more towns, including Westport and Fairfield, report the vines in their communities, she said.

Even with positive results, Ellis said it's still too early to call the effort a success.

"We are not out of the woods yet," Ellis said. "The vines are still vigorously growing, but all indicators are that the weevils are establishing well at the sites."