The plant, called mile-a-minute weed, moves a little slower than that, but not much, strangling trees and native plants in its path. It grows as much as 6 inches a day and it is prolific: A single plant can produce 2,000 seeds that can be spread by birds, animal fur, and water.
That suits the weevils, Rhinocominus latipes, just fine. Mile-a-minute is all they eat.
The Maryland Highway Administration released weevils this summer at seven wetlands, including one in Jessup, Md. Four more sites are on the schedule. The state is spending $25,000 on the bug program this year.
On a recent tropical morning, Bob Trumbule carried a soft-sided blue cooler into the woods, past some small patches of mile-a-minute as he sought the mother lode. Inside the cooler, the weevils awaited the dinner bell.
Trumbule, an entomologist with the Maryland Department of Agriculture, crossed a clearing to a large thicket of the vines where a few Japanese beetles munched away.
While the Japanese beetles do more immediate damage to mile-a-minute by devouring entire leaves, the weevils lay waste to the whole plant over time, Trumbule explained. The weevil eggs produce larvae that burrow into stems to kill the plant and prevent the release of its seeds.
As far as the state is concerned, mile-a-minute has no redeeming qualities. It can take over vast tracts, especially where the soil has been disturbed for highway construction. Yet the plan is not to eradicate the weed. The state wants to leave just enough to keep the weevil population healthy, Trumbule said, "bringing everything back into balance."