The emerald ash borer (EAB), Agrilus planipennis, is an eastern Asian beetle that belongs to the metallic wood-borer family (Buprestidae). EAB was discovered in southeastern Michigan near Detroit in the summer of 2002. It has since become established in Michigan, Ohio, Indiana, Virginia, Pennsylvania, Maryland, New York and Ontario. In the central United States, it has killed green, white, and black ashes in forested and landscaped settings and is spreading towards Connecticut. This species poses a significant threat to ash trees, which are an important component of many Connecticut forests (a recent study estimated that Connecticut forests have nearly 25 million ash trees). Ash trees in Connecticut may be predisposed to attack because many already are stressed by infections of one or more plant pathogens. Ashes are valued highly for shade trees, furniture, baseball bats and firewood. With interstate movement of wood and nursery stock and with international shipment of solid-wood packing material, it is critical to monitor this situation so as to protect forests and ornamental shade trees in Connecticut.
What to Know About Emerald Ash Borer
- It attacks only ash trees (Fraxinus spp.).
- Adults are dark metallic green, a half-inch long and one-sixteenth of an inch wide.
- Larvae are flat, legless, heavily fragmented, creamy white, and reach one inch in length when fully mature
- Adults leave a D-shaped exit hole in the bark when they emerge in spring.
- Woodpeckers like EAB larvae; heavy woodpecker damage on ash trees may be a sign of infestation.
- It probably came from Asia in wood packing materials
- Regulatory agencies and the USDA have started enforcing quarantines and fines to prevent potentially infested ash trees, logs or hardwood firewood from moving out of areas where EAB occurs.
- There are several different insecticide options that can be administered for controlling EAB depending on the health of the tree (trunk injections, soil injections, lower trunk sprays and cover sprays)
- There is still ongoing reseafch on how to best control EAB
How do I tell if my ash tree has been infested by emerald ash borer?
Common signs of infestation include D-shaped exit holes through the bark about one-eighth of an inch wide, S-shaped larval galleries just beneath the bark, thinning canopy, vertical splits in the bark, and unusual shoots sprouting from the main trunk or base of the tree.
What is the lifecycle of emerald ash borer?
Emerald ash borer produces only one generation per year. Adults emerge from late May through early August, with emergence peaking in early July. They feed on foliage for one to two weeks prior to mating. Females produce about 50 to 100 eggs, which are laid individually on the bark surface or within bark cracks and crevices. As larvae hatch, they tunnel into the tree, where they feed on the phloem and outer sapwood. Larvae continue to feed through summer and into the fall, with most completing their development prior to over-wintering in the outer bark or just under the inner bark within the outer inch of sapwood. Pupation occurs in mid- to late-spring. Adults emerge soon thereafter to complete the cycle.
How does emerald ash borer spread?
After emergence from their host tree, emerald ash borer adults fly (in general as far as one-half mile) to nearby ashes to mate and lay eggs. In addition, humans can contribute to the rapid spread of this beetle. The Ohio and Maryland infestations have been traced to infested nursery stock imported from Michigan before the insect was discovered. Transport of firewood and other ash materials from infested areas is another way it is spread.
What damage does emerald ash borer cause?
Emerald ash borer larvae tunnel under the bark of the host tree, feeding on the phloem tissue. The damage caused by the larvae disrupts the flow of nutrients between the tree’s roots and canopy. This damage results in canopy thinning, branch dieback, and eventually tree death. Larvae can destroy ashes within two to four years, but a heavy infestation could kill a tree in as little as one year.
In order to prevent or lessen the spread of invasive pests, please do not transport firewood more than 50 miles from its source.