Weevils on the Loose

Arlington has recently acquired a new tool in the battle against invasive plants — weevils. Rhinoncomimus latipes, otherwise known as the mile-a-minute weevil, has been found in several locations around the County. Although the weevil was not released in Arlington, it has traveled here from nearby jurisdictions such as Fairfax County or Washington, D.C. In the past few years, these jurisdictions have released small populations of the mile-a-minute weevil into parkland. The weevils are a form of biological control for Persicaria perfoliata, a particularly aggressive invasive vine otherwise known as mile-a-minute weed.

Mile-a-Minute Weed

Mile-a-minute weed. Photo courtesy of Dr. John Meade, weed scientist emeritus, Rutgers NJAES Cooperative Extension.

About Mile-a-Minute Weed

The Department of Parks and Recreation (DPR) has identified infestations of mile-a-minute in several parks and natural areas. These locations include Windy Run Park, Long Branch Nature Center, Bluemont Park and others. Mile-a-minute weed is an annual, herbaceous vine with prickly stems and triangular leaves. Like its name suggests, this vine can grow very quickly, and will often climb over other plant and up into the tree canopy. Mile-a-minute can create up to 2,000 seeds per plant and spreads into other park areas, causing impacts to the negative vegetation.

Mile-a-Minute WeevilAbout the Mile-a-Minute Weevil

In 2004, the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS) approved the release of the mile-a-minute weevil in the U.S. The New Jersey Department of Agriculture began mass rearing the weevil in 2004 and the first release was made in Delaware that same year. Years of research were done by APHIS, and other organizations to ensure that mile-a-minute would be the only host plant for the mile-a-minute weevil.

The weevils can be observed directly in the field and are usually spotted on the terminal leaves of a plant. The adults are about 2 millimeters long and are black. Later in the season, they may be covered by an orange film that appears after they have started feeding. The feeding damage on the leaves and stems is also a good way to find out if the weevils are present.

Impact on Mile-a-Minute Weed

Research has shown that the weevils don’t necessarily kill the mile-a-minute plants, but delay seed production and stunt the plants by causing more branching of the stems. The weevil damage allows other plants to compete with mile-a-minute more effectively. DPR has started a pilot management program at Fort C.F. Smith in a meadow area infested with mile-a-minute. Weevils were found at the site this summer. Planting native plants, such as goldenrod, will, in addition to the damage caused by the weevil, minimize the growth rate and seed production of mile-a-minute. Next season, we will be able to see what effect the weevil and other management techniques had in this site.