How the Emerald Ash Beetle came to America

Agrilus planipennis, better known as the highly destructive, emerald ash beetle of Asian origin, was first discovered in the United States in June of 2002 in southeastern Michigan, but scientists believe this destructive insect arrived in North America long before this; as early as the 1990s in something as innocuous as a shipping container, pallet or blocks used to stabilize cargo.

While great attention is paid to cargo shipped into the US, little notice is given to the containers or pallets used in their packing, or what insects these materials might harbor. Now, with the wide spread destruction of millions of ash trees in North America and the prospect of the ash tree being eradicated, containers are getting more attention and while this might stop another exotic species from coming to America, it is too little-too late with regard to the emerald ash borer beetled.

Laws in many of the infected North American states as well as Canada, prohibit moving ash from one area to another in an effort to slow the spread of the emerald ash beetle into uninfected areas, but it may be too late for this. Between 2002 and 2008, the insect spread to Ohio, Indiana, Illinois, Maryland, Pennsylvania, West Virginia, Missouri and Virginia.

In addition to prohibiting movement of the ash tree and its wood, scientists are trying to find a “fix” for the problem. Some states have adopted the use of preventive pesticides but this has proved to be very expensive. Some have tried cutting all ash trees within a mile range of an infested tree, but this too is expensive.

The most promising solution seems to be importing and releasing a predator that feeds on the emerald ash beetle: the tiny sting-less Asian wasp, which lays its eggs on the larvae of the ash beetle. When the wasp eggs hatch, they feed on the ash beetle larvae, thereby destroying it.

As with any release of an exotic species, scientist don’t yet know what other impact the wasp might have. Could they create havoc in a yet to be discovered area of the eco-system? We just don’t know yet and at best it’s a gamble but as long as the inhabitants of earth continue to be internationally mobile, the threat of transporting harmful insects remains a threat.

In the mean time, efforts to slow the spread of the emerald ash beetle are helping but there are still millions of ash trees dying each year. Had we learned sooner how and when the emerald ash beetle came to America, perhaps we would be further ahead in the fight and less states would be infested. Perhaps, we have learned an important lesson.