Insect Threatens the Forests

Bridge over a depression in the woods in summer.

NPS/Tom Jones

A new insect pest, the emerald ash borer, is a major threat to ash trees in American forests. Its impact is expected to be as devastating as the chestnut blight and Dutch elm disease, two fungal diseases from Asia that caused massive tree die-offs in the early twentieth century. These accidentally introduced diseases permanently changed what trees grow in forests and cities. Ash is one of the most common Ohio trees. Ash thrive under diverse conditions: in clay or limestone soils, along streams, and in moist bottomlands. All property owners with ash trees near buildings, roads, and other valuable “targets” must prepare for when these trees die and become potential hazards. Researchers have already begun studying what happens when emerald ash borer opens up gaps in the forest canopy. If invasive plants move in to crowd the understory, this could affect native wildflowers, tree seedlings, and soil and water chemistry.

 

Emerald Ash Borer

USDA

Emerald Ash Borer

The emerald ash borer (Agrilus planipennis) is an Asian wood-boring beetle that kills ash trees three to five years after infestation. Adults are dark metallic green, and fly from May through September to ash trees to mate and lay eggs. Larvae emerge and tunnel beneath the bark, chewing on vascular tissue and interrupting the tree’s circulatory system. An infestation only becomes apparent once the canopy thins, branches die back, and death begins. By then, the insect has long since moved on. Emerald ash borer was first identified near Detroit, Michigan in July 2002. Unfortunately, the insect continues to disperse, already killing millions of ash trees from Illinois to Maryland and up into Ontario. It is in at least 26 Ohio counties, including those in and near Cuyahoga Valley National Park.

Firewood Quarantine

The Ohio Department of Agriculture had imposed quarantines on counties known to be infested by the emerald ash borer, but they have since been lifted. For more information about this and other invasive pests, visit The Ohio Deparment of Agriculture's website.