Asian longhorned beetle discovered in Ohio

The Asian longhorned beetle was recently found in southwestern Ohio and poses a serious threat to a number of tree species found in the state. It prefers all species of maples, as well as birches, elms, willows, horse chestnuts and buckeyes. Other tree species that may be a host for the Asian longhorned beetle, but are rarely attacked, include ashes, European mountain ash, hackberry, London plane tree, mimosa and poplars.

Last week, Gov. John Kasich signed an order restricting the movement of hardwood logs, firewood, stumps, roots and branches out of Tate Township in Clermont County to help prevent the spread of the beetle. The order is effective immediately and also restricts the sale of nursery stock, green lumber and logs of the following trees: maples, horse chestnut, buckeye, mimosa, birch, hackberry, ash, golden raintree, katsura, sycamore, poplar, willow, mountain ash and elms.

Working with the Ohio Department of Agriculture, the U.S. Department of Agriculture confirmed the presence of beetle in Tate Township, which is about 30 miles southeast of Cincinnati. Dan Herms, specialist in wood-boring insects with Ohio State University Extension and the Ohio Agricultural Research and Development Center, hoped the Asian longhorned beetle would never be detected in Ohio. It poses a serious threat to Ohio's trees, including all species of maples, which are among the most abundant tree species in Ohio's natural and urban forests.

It is a large beetle with very few look-a-likes in North America. It is up to 1.5 inches long with a very long black and white banded antennae. Its body is dark blue to bluish-black with distinctive irregularly-shaped and -sized white spots. It produces a dime-sized exit hole in the bark, which can result in the trunk being riddled with exit holes. Adult emergence holes are circular and very large measuring up to a half-inch in diameter. Although the beetles are capable of flying several hundred yards in search of a suitable host, they prefer to remain close to the tree from which they developed in order to re-infest the tree if it will support another generation. After mating, females chew an oblong-shaped pit through the bark and phloem, depositing a single egg. Females are capable of laying 35-90 eggs during her lifetime.

The pits and adult exit holes, if found on living branches and stems, are strong diagnostic indicators for an Asian longhorned beetle infestation. The beetles are classified as "round-headed borers." The segments towards the front of the fleshy, thin-skinned, yellowish-white larvae are larger in diameter than the rest of the segments. This makes the larvae look like they have round heads and tapering bodies. Early larval feeding activity produces weeping canker-like symptoms on the bark. Later larvae stages bore deep into the white wood.

Signs of infestation include perfectly round three-eighths to half-inch exit holes made by adult beetles when they emerge from trees; the pockmarks on tree trunks and branches where female beetles deposit eggs; wood shavings and saw dust produced by larvae feeding and tunneling; early fall coloration of leaves or dead branches; and running sap produced by the tree at the egg laying sites or in response to larval tunneling. According to Ohio Department of Agriculture, the beetle could decimate maple trees in Ohio, threatening up to $200 billion in standing timber, hurting maple sugar processors, damaging the state's multi-billion dollar nursery industry and diminishing Ohio's popular fall-foliage season.

Discovering this damaging insect early in Ohio is important. Unlike unsuccessful eradication attempts for the emerald ash borer in Ohio and other infested states, the Asian longhorned beetle is being effectively contained in the other four states with known infestations -- Illinois, Massachusetts, New Jersey and New York -- and in Ontario, Canada.

Jul 1, 2011