By Henry W. Art
A walk along a backcountry road this summer revealed what looked like a cylindrical beach toy hanging in a white ash tree. The green spiraling upside-down pagoda-like thing suspended 30 feet above the ground was guyed by nylon ropes to which a note with the title “What is that Green Thing Hanging in the Tree?” was attached. The device, installed by the MA Department of Conservation and Recreation (DCR), was a trap for monitoring the presence of the emerald ash borer (EAB), a 1/3-inch-long, iridescent elongated beetle that arrived in our region settling in Dalton less than two years ago. The reason for going to the trouble of hanging ornate traps high in ash trees around the county is that these bugs, native to eastern Asia, lay their eggs in crevasses on the bark of ash trees, and when the larvae hatch, they burrow into the trunk. For a year, or sometimes two, the grubs consume vast amounts of the tree’s inner-bark tissues. The result is usually the death of the tree from within. The shiny green adults emerge in late-spring or early summer through 3/16-inch, D-shaped holes to find a mate and produce the next generation.
It is not known with certainty how the EAB were transported from Asia to the Detroit, Michigan metropolitan area, but the leading speculation is that eggs or grubs were castaways in wooden pallets used in international shipping. It took a while after their introduction sometime in the1990s to realize that the exotic insect would cause major problems. The emerald ash borer was actually identified for the first time in the US only in 2002 and since then its populations have been exploding, killing tens of millions of ash trees that grow along city and town streets, and sometimes 99% of tree-sized ash in the surrounding forests, as they spread outward from southeastern Michigan.
The recent arrival of the EAB in the Berkshires is not good news for our ash trees, which are important forest species in terms of both their ecology and economic value. White ash and black ash both are abundant in Berkshire Forests, producing very strong, yet relatively light-weight woods with an exceptionally straight grain, making these species ideal for baseball bats, specialty wood items, baskets, and even firewood. Ecologically these abundant trees are important wetland indicator species throughout the region.
Changes in the composition of our forests are being monitored at Williams College’s Hopkins Memorial Forest (HMF) in Williamstown, MA. At the HMF a series of over 400 permanent plots, each a quarter-acre in area, was established in 1935, and periodically every tree larger than ½” thick has its diameter measured and its species recorded in each plot. From these surveys we know that white ash was thriving in the 1930s through the 1970s, but then a somewhat mysterious disease called “Ash Yellows” swept through the region so that by the mid-1990s half of the white ash in the Hopkins Forest were dead. Although recently the rate of ash dying from the yellows has declined a bit, perhaps indicating that there is some resistance to the disease among the survivors, the EAB represents an additional and different threat. It could make a tree once considered to be a premier timber species into a rare commodity.
Can the spread of EAB be stopped and the destruction of ash species controlled? Since forest-wide insecticide applications are neither economically feasible nor environmentally acceptable, it is hoped that effective biological control agents eventually can be developed. Native non-stinging wasps such as the smoky-winged beetle bandit have been found to feed their young by catching beetles such as the emerald ash borer. Other species of insects, bacteria, and fungi parasitize the EAB. It remains to be seen whether the populations of these control agents will increase to the extent that they can check or reverse the devastating impacts of EAB.
As forest researchers and federal and state forest managers monitor EAB populations and attempt to develop effective means of control, the Commonwealth of Massachusetts on 1 March 2013 established quarantine, restricting the transport of ash nursery stock, untreated ash lumber, and firewood into and out of a zone that includes the entirety of Berkshire County. This is where the help by the public is essential to prevent the inadvertent spread of a major forest pest. Buy firewood for campfires, or even burning in woodstoves, from local suppliers, or at least purchase firewood that has been certifiably treated to destroy emerald ash borers.
The public can also play an important role in the monitoring efforts by reporting sightings of emerald ash borers to Ken Gooch, Director of the DCR Forest Health Program at 413-253-1798 ext. 204, or contact the MA Department of Agricultural Resources at their website: http://massnrc.org/pests/report.aspx.