Forest Society Hosts State Tests of Invasive Beetle Controls

Forest health specialists with the state’s Division of Forest and Lands released tiny wasps near the Forest Society’s Concord headquarters in June in a project to test biological control measures for the Emerald Ash Borer, the invasive beetle that kills ash trees.

The Forest Society’s Merrimack River Outdoor Education and Conservation Area is one of several test sites where state scientists are measuring the effectiveness of various potential controls of the beetle. The tetrastichus wasp, a non-native species provided by the federal Animal Plant Health Inspection Service, lays its eggs in EAB larvae, which become food for wasp larvae. EAB is an Asian species with no natural predators in the U.S.

The state’s first known population of EAB was found in Concord in March of 2013 and since then has also been detected in Canterbury, Loudon and just south of the New Hampshire border. A quarantine on moving hardwood firewood, ash wood products and ash nursery stock out of Merrimack County remains in effect.

Emerald ash borers harm true ash trees and when left unchecked can cause the death of all trees in an area within five to 10 years. The pest has spread eastward from where it was first discovered near Detroit, Mich., in 2002.

Ash makes up approximately 6 percent of the trees in New Hampshire’s northern hardwood forests, or about 25 million trees, according to Brad Simpkins, state forester at the Division of Forest and Lands at the Dept. of Resources and Economic Development (DRED). Because ash trees are a common landscape tree and have been used frequently in urban landscapes to replace American elm when that species suffered from Dutch elm disease, the effect of a possible widespread infestation would be seen along city streets. The detection in Concord is the first for New Hampshire and is the easternmost detection in North America.

Simpkins estimated that ash makes up one percent, or 2.6 million board feet, of the 223 million board feet of wood harvested annually in New Hampshire, representing approximately $500,000 in stumpage income to landowners and $1.15 million in lumber at the mill.

For more information about EAB and other invasive pests, go to