Losing Our Ash Trees to Beetles


(This 908th Buffalo Sunday News column was first published on August 17, 2008)



Emerald Ash Borer beside Ash Galleries

U. S. Forest Service


The future of ash baseball bats and other ash products is clouded by the apparently accidental introduction of a small beetle to North America. It evidently came in wooden packing products from eastern Asia.


This insect, the emerald ash borer, has already destroyed an estimated twenty million ash trees in Michigan and adjacent Ontario. Almost as many additional trees are now infected and dying there and in seven other states including Pennsylvania. Closest to us in western New York is the infestation discovered less than a hundred miles west of us near Long Point on the north shore of Lake Erie.


Ash wood is both strong and resilient. These qualities make it useful for making bows, pool cues and tool handles as well as bats. It is extensively used for office furniture veneers and for electric guitar bodies and it makes excellent firewood. Its bark is a source of blue dye and in the Orient tea made from this bark is a medication for diarrhea and eye discomfort.


The value of these trees to the forest product industry is significant. More than 7.5 billion ash trees are currently at risk. Nearly 43,000 cubic yards of ash saw timber with a value of over $25 billion are harvested in the eastern United States each year.


Ashes have environmental value as well. Here in western New York they are common street and yard trees and these trees already suffered from the October 2006 snowstorm. We lost four of them at that time. The branches of those 70-foot trees could not hold the weight of the snow trapped on their leaves and that first frightening night we were forced to listen as they crashed down on our roof and yard. We no longer have their wonderful shade and our summer air conditioning bills reflect their former value.


Now even those ash trees that made it through that storm are threatened, so we had better get ready for an invasion by this destructive insect. (Note: Only ashes of the genus Fraxinus are attacked by this beetle. Those are the green, white, black and blue ashes and their nursery cultivars. Mountain ashes belong to a different genus and are safe from its depredations.)


The emerald ash borer is a small beetle only about a half-inch long. It has a metallic green head and wing covers and a reddish or purple abdomen. There are other green beetles with which it might be confused. Two in this region are the six-spotted tiger beetle and the caterpillar hunter, but those are less often seen in trees.



Borer in Gallery


The adult borers cause only minor damage. All they do is feed on leaves. The damage is done by their whitish wormlike larva. The adult female beetle lays 75 to 300 eggs in bark crevasses and, when the larva hatch, they bore through the tree bark to form tunnels, called galleries, in the ash's phloem. These galleries disrupt the flow of water and nutrients through the tree and over time branches in the upper canopy die as does finally the entire tree -- usually in about two years. A close examination of infested trees will disclose eighth-inch D-shaped holes through which the adult beetles have exited.


The United States Department of Agriculture and individual states have invested millions of dollars in an effort to halt the spread of these beetles, first by removing all ashes within a half-mile of the earliest Michigan outbreaks. Clearly that did not work. They have also prohibited movement of wood products including firewood of any hardwood tree from states in which the borers have been identified. New York officials have established sentinel trees to detect beetles near the state borders, thankfully with none yet identified. But still the spread continues and it is widely believed that this alien beetle will reach all parts of the North American continent.


So add the emerald ash beetle to the "Most Wanted" list of our silvacultural post office, next to the Asian long-horned beetle, the bronze birch borer, the dogwood borer and other woodland villains.


I recall the loss of our elms and still earlier our chestnuts were lost as well. I don't look forward to the loss of another species.-- Gerry Rising