Tree-Killing Insect from Asia Found in Rhode Island

By ecoRI News staff

An emerald ash borer. (istock)

An emerald ash borer. (istock)

The emerald ash borer, a destructive forest insect from Asia, has been found for the first time in Rhode Island, according to the Department of Environmental Management (DEM). The state has joined the federal quarantine covering much of the eastern United States to slow the spread of this alien invader.

Officials with the Animal and Plant Health and Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA) have confirmed the identification of a beetle recently found in Washington County. The insect, which attacks only ash trees, was captured during annual monitoring surveys conducted jointly by DEM, the University of Rhode Island, and the USDA.

With many more traps collected from around Rhode Island now being examined, it’s highly likely that there will be more positive emerald ash borer identifications to be announced, according to DEM.

The emerald ash borer accidentally arrived in North America via wooden packing material exported from China and was first detected in Detroit in 2002. The invasive pest overwinters as larva under the bark of ash trees. As they grow, larvae feed and zigzag through tree tissue, leaving S-shaped tunnels that cut off the tree’s ability to transport water and nutrients. Once infested, ash trees rapidly decline and are killed in three to five years.

In Asia, emerald ash borers have co-evolved with native ash trees, so there are natural enemies and pathogens that keep their levels in check. That isn’t the case in North America, where there are very few if any known enemies and pathogens to control the insect.

An ash tree in Canada felled by emerald ash borers. (istock)

An ash tree in Canada felled by emerald ash borers. (istock)

Emerald ash borers has been detected in 35 states, including Connecticut, Massachusetts, and Rhode Island, and in three Canadian provinces. Since its discovery, the insect has killed tens of millions of ash trees and has cost municipalities, property owners, nursery operators, and forest products industries tens of millions of dollars, according to APHIS.

Although ash trees constitute only about 1 percent to 2 percent of Rhode Island’s forests, ash has been widely planted in urban public areas as landscape and shade trees on streets, campuses, parks, and urban woodlots. A compromised ash tree may represent a potential risk to health and safety because of the public use of these areas, according to DEM.

Emerald ash borers threaten all ash species in Rhode Island, including white ash, green ash, and black ash. There are no proven means to control these insects in forested areas, though repeated pesticide treatments can help protect individual trees, according to DEM.

Emerald ash borers don’t pose any human health risk.

DEM is finalizing an action plan aimed at slowing the spread and assisting Rhode Island landowners and municipalities in raising awareness of emerald ash borers and other invasive pests, identifying and inventorying ash trees, and reducing risks. DEM’s Division of Forest Environment is preparing a guidance document to help communities and homeowners develop response plans.

Slowing the spread of this insect is important, according to DEM. Adult emerald ash borers can fly only short distances, but people have accelerated their spread by moving infested material, particularly firewood. Larvae are easily moved in firewood, logs, and nursery stock, because they are hard to detect under bark.

Residents and visitors are reminded to protect Rhode Island’s forests by buying and burning local firewood. Wood dealers, loggers, and arborists should check state and federal restrictions prior to transporting ash out of Rhode Island. DEM has adopted the Don’t Move Firewood campaign developed by The Nature Conservancy.

To report a suspected exotic or invasive insect or plant, fill out the DEM Invasive Species Reporting Form.