Biology
Emerald ash borer (Agrilus planipennis) is an invasive, wood-boring beetle native to Asia. Its larvae feed in the tissue just beneath the bark, cutting off the tree's ability to move water and nutrients and killing virtually all untreated ash within a few years. Understanding the beetle's appearance, life cycle, and the signs of an infestation is the first step in detecting and slowing its spread.
Identification
Metallic emerald-green adult, about 1/2 inch long, with a coppery-red upper abdomen visible under the wing covers.
Life Cycle
A one- to two-year cycle: adults emerge in late spring, lay eggs in bark crevices, and larvae feed through summer and fall.
Larvae & Galleries
Cream-colored larvae carve winding, S-shaped galleries under the bark that disrupt the flow of water and nutrients.
Host Trees
All true ash (Fraxinus) species are at risk - green, white, black, and blue ash, including landscape and shelterbelt trees.
Signs & Symptoms
Canopy dieback, D-shaped exit holes, bark splits, epicormic sprouting, and heavy woodpecker activity.
How It Spreads
Adults fly only short distances; long-distance spread is driven by people moving infested firewood, logs, and nursery stock.