By PAUL HETZLER

A pretty green bug that kills ash trees by the millions is on the North Country's doorstep.

It’s not Dorothy’s fault, or even that of the Wizard of Oz, but the emerald city isn’t what it used to be. By “emerald city” I mean Fort Wayne, Indiana. Naperville, Illinois. Dayton, Ohio. Or any number of Midwestern communities that are decidedly less green than before the emerald ash borer (EAB) arrived there.

Since its discovery in 2002, the EAB has drastically altered the face of the above-mentioned “emerald cities,” and many others as well. Formerly tree-lined streets in those areas are now barren and stark, entire neighborhoods stripped of ash trees because of the emerald invader. And it’s headed to northern New York State. The New York State Department of Environmental Conservation (NYSDEC) has announced that the fourth annual Emerald Ash Borer Awareness Week will be May 17-23, 2015.

For such a destructive pest, the EAB is actually beautiful. It’s a small (3/8” to ½”) bullet-shaped beetle that would be easy to overlook if not for its bright, metallic, emerald-green color with shiny copper highlights. The beetles themselves do little harm, but their immature stage (larvae) feed on cambium, the living tissue between the inner bark and the wood, of ash trees, girdling and thus killing them.

Since the EAB kills only true ash, those trees in the genus Fraxinus, mountain ash, isn’t targeted. But aside from the relatively few ash that will be treated with insecticides (at some expense) through the estimated 15-20 year duration of an EAB infestation, all of New York State’s 900 million ash trees will disappear.

With EAB literally right on our doorstep to the north, there’s no way to keep it from reaching the North Country. In fact, given that it’s been found in two locations in southern Ontario just across the St. Lawrence River, its arrival is imminent in St. Lawrence County, and potentially northeast Jefferson and northwest Franklin Counties as well. Emerald ash borers are quite capable of flying across the river, and you can bet they won’t be checking in with the Border Patrol.

There are many things we can do to prepare for the this insect. Towns and villages need to know how many ash trees they have in order to figure removal costs and plan accordingly, and also to locate ash trees of good health and form that they may want to preserve. While some towns have tree inventories, most do not, and some of those may welcome volunteer help to survey ash trees.

Learning the hallmarks of an EAB infestation and scouting for possible cases is also important. When adult EAB emerge in June from an infested tree they make a distinctive D-shaped exit hole, with the straight part of the D on the bottom. While it has a unique shape, this hole is tiny—1/8” across—and very hard to see.

A conspicuous symptom is the sprouting of branches directly out of the trunk. This is called epicormic sprouting, and is a response to severe stress. Bark splitting is another indicator. Heavy woodpecker activity on an ash trunk (flaking off of the outer bark, not the typical excavation of cavities) is a particularly noticeable sign. Communities such as Hammond, Morristown, Massena, and the Mohawk Nation at Akwesasne should be especially vigilant in scouting for EAB this year. Report all suspected cases of EAB infestation to the NYSDEC or your Cornell Cooperative Extension office.

It’s recommended that homeowners who want to treat their ash trees begin doing so when EAB is confirmed within 15 miles. Even ash trees showing symptoms of infestation can often be saved if treatment is begun quickly enough. Insecticides have been proven to be effective, and their cost is coming down. Options can be found at www.emeraldashborer.info as well as at your closest NYSDEC or Extension office.

Planning, cooperation and community involvement are the keys to weathering the EAB storm while preserving as many ash trees as possible, and without breaking the bank. Devastated areas in the Midwest are already replacing street trees (with a far greater diversity of species), turning their communities emerald again. Dorothy would have approved.

Paul Hetzler is a forester and horticulture and natural resources educator with Cornell Cooperative Extension of St. Lawrence County.