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Selected Articles Another Year, Another Issue: Emerald Ash Borer by Dave Horn "If it isn't one thing, it's another" could be the entomologist's motto. Central Ohio's latest invasive insect is the Emerald Ash Borer (EAB). The EAB is a member of the Metallic Wood-boring Beetle family (Buprestidae), whose larvae ("flat-headed borers") eat the cambium under a tree's bark. Cambium is the living tissue that produces new channels for movement of water and nutrients within the tree. Destroy the cambium and you kill the tree. You can do that by girdling the trunk, and flat-headed borers can do it too, if there are enough of them. The EAB is a small (1/2 inch long), slender, attractive native of the Orient, first detected near Detroit in 2002. (It might have arrived in the USA a few years earlier.) Despite aggressive efforts by state and federal authorities to limit its dispersal, the EAB has spread from Michigan into four northwestern Ohio counties. Of more concern is long-distance movement: last year EABs were found in Maryland and in Columbus (near Easton). This movement is probably by EABs being transported in nursery stock and/or firewood. Lesson #1: Do not move firewood from an infested to an uninfested area. Like many invasive species, the EAB has few natural enemies in the U.S., so numbers skyrocket, and millions of ash trees in Michigan have already succumbed. All ash species are affected, and the worst-case scenario sees the elimination of ashes from the forests of North America, just like the loss of American elm and American chestnut in the last century. Entomologists have begun searching the Orient for suitable biological control agents that might be imported. There is also a possibility that native predators will add EABs to their diet as the beetles become more common and widespread. Woodpeckers love eating larvae of wood-boring insects and have been shown to be major mortality factors for some forest pests. Sometimes, but not always, an invasive pest species is brought under control by a complex of predators, parasites and host plant resistance. Meanwhile, what can be done? The central Ohio infestation is very localized so far, and aggressive management may contain or even eliminate EAB from Franklin County. You can help by noting any suspected infestations. Look for ash trees with small D-shaped exit holes, dieback of upper branches, and/or new sprouts clustered around the base of the tree. When you're out birding, note if woodpeckers seem to show an unusual interest in specific ash trees. Symptoms should be reported to the Ohio Department of Agriculture, 888-OHIO-EAB. For more information, call the above number or visit: Dave Horn is Professor of Entomology at the Ohio State University. He is vice president of Columbus Audubon, chairman of our conservation committee, Avid Birder participant, and reformed Hell's Birder. (If you don't know what a Hell's Birder is, you can find out here.) Back to Newsletter Articles Index Page Page updated 01/20/04 © Columbus Audubon 2004
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