Emerald ash borer (EAB), a native beetle of Asia, invaded North America in the 1990's by way of wooden packing material. In a decade's time, these pests killed tens of millions of trees throughout the Great Lakes region. Get to know this pest, so you can sound the alarm if it makes its way to your neck 'o the woods.
The adult emerald ash borer is a striking metallic green, with an iridescent purple abdomen hidden beneath the forewings. This elongate beetle reaches about 15 mm in length, and just over 3 mm in width. Look for adults from June to August, when they fly in search of mates.
Creamy white larvae reach lengths of 32 mm at maturity. The prothorax nearly obscures its tiny, brown head. EAB pupae also appear creamy white. The eggs are white at first, but turn deep red as they develop.
To identify emerald ash borer, you should learn to recognize the signs of an infestation. Unfortunately, symptoms of emerald ash borer don't become obvious until two or more years after borers enter a tree. D-shaped exit holes, just 1/8" in diameter, mark the emergence of adults. Split bark and foliage dieback may also portend pest trouble. Just under the bark, S-shaped larval galleries will confirm the presence of EAB.
Emerald ash borer larvae feed only on ash trees. Specifically, EAB feeds on the vascular tissues between the bark and sapwood, a habit that interrupts the flow of nutrients and water required by the tree.
All beetles, including the emerald ash borer, undergo complete metamorphosis.
Egg – Emerald ash borers lay eggs singly, in crevices in the bark of host trees. A single female can lay up to 90 eggs. Eggs hatch within 7-9 days.
Larva – Larvae tunnel through the tree's sapwood, feeding on the phloem. Emerald ash borers overwinter in the larval form, sometimes for two seasons.
Pupa – Pupation occurs in mid-spring, just under the bark or phloem.
Adult – After emerging, adults remain within the tunnel until their exoskeletons properly harden.
Special Adaptations and Defenses:
The emerald ash borer's green color acts as camouflage within the forest foliage. The adults fly quickly, fleeing from danger when needed. Most buprestids can produce a bitter chemical, buprestin, to deter predators.
Emerald ash borer require only their host plant, ash trees (Fraxinus spp.).
Emerald ash borer's native range includes parts of China, Korea, Japan, Taiwan, as well as small areas of Russia and Mongolia. As an invasive pest, EAB now lives in Ontario, Ohio, Indiana, Illinois, Maryland, Pennsylvania, West Virginia, Wisconsin, Missouri and Virginia.
Other Common Names: