Battle bugs: Rhode Island deploys predator beetles from Virginia to protect hemlock trees against invasive insects
Rhode Island is mobilizing a small army of “tiny but mighty” bugs to help save its majestic hemlock trees.
Brought into the Ocean State from Virginia, the predator beetles named Laricobius nigrinus were released in the Richmond woods earlier this month, so they can eat a tiny, invasive insect called the hemlock woolly adelgid, which attacks hemlock trees.
The beetles are “pretty hungry predators,” said Alana Russell, a research assistant with the University of Rhode Island Biocontrol Laboratory. “They’re tiny but mighty.”
Only about one-tenth of an inch in size, the beetles have been brought to Rhode Island to protect trees that can grow to 100 feet tall and live 800 years.
There’s no common name for Laricobius nigrinus, so researchers like Russell use a nickname for the little warrior: “Lari.”
In this battle of the bugs, Lari will square off against an even smaller insect that is native to Japan, and found its way into to the United States in 1927, according to the University of Massachusetts. The hemlock wooly adelgid attacks the Carolina and eastern (Canadian) hemlock and can kill previously stressed plants within three to five years, according to UMASS.
A problem in much of the Northeast, including all of New England, wooly adelgids were detected in Rhode Island in the late 1980s, according to Lisa Tewksbury, director of the URI Biocontrol Laboratory. The insects were already established in Connecticut, and it’s believed Hurricane Gloria, which hit the East Coast in 1985, could have blown them into Rhode Island, Tewksbury said.
The National Park Service describes the eastern hemlock as “a graceful native evergreen tree.” The trees typically grow to 60 or 70 feet tall but can reach 100 feet and three feet in diameter, according to the New England Forestry Foundation. Eastern hemlocks can live more than 800 years, “rivaling some of the giant trees of the Pacific Coast,” the foundation says.
Woolly adelgids can kill the magnificent trees by sucking their sap. The insects can also stunt new growth, and that seems to be the primary impact so far in Rhode Island, according to Russell. “I think a good portion of our hemlock population is really in the stress state,” she said.
Tewksbury said, “We’re in a position where we’d like to protect our hemlocks and encourage them to continue.”
The beetles have been used in other states to fight the woolly adelgid threat. The local project is part of a cooperative effort between URI, the state Department of Environmental Management, the federal government and Virginia Tech.
Virginia Tech had enough beetles to spare and offered some to URI. The beetles are not native to Rhode Island, so Tewksbury had to ensure the project had permitting from the federal government.
That’s what sent Russell into the woods of Richmond on March 2 armed with 100 bugs. She was immediately encouraged as she watched beetles crawl off and “start smelling” for their foes.
Researchers hope the beetle population grows and Lari keeps fighting for years. “We have high hopes,” Russell said.
By Jack Perry