Emerald Ash Borers
Facts about Emerald Ash Borers
A new threat to ash trees in North America is that of emerald ash borers; an insect whose natural range has always been recognized to be eastern Russia, Japan, Korea and northern China. Its presence has been known in the United States only since 2002.
There is no way to know how the emerald ash borers became ensconced in the United States. However, some speculate that international trade may have been the conduit that brought them in; either in packing materials for incoming cargo or for stabilizing supports for cargo. In any case, they were first seen in Michigan in 2002; originally believed to have been in six separate counties. Since that time, it has been discovered that the borers were much more widespread, with the ultimate result being that only a minuscule part of the state is not affected by their presence. The emerald ash borers are now also in 11 other states and Canadian provinces, including Indiana, Ohio, Wisconsin and Pennsylvania.
Identification of the emerald ash borers is easy. The adult beetle is very small; measuring around ½ an inch long. Their bodies are metallic green and very narrow, with shiny, iridescent undersides as well. As adults, these pests live only between 3 to 6 weeks. Eggs are laid after mating in clutches of 60 to 90 eggs, with the female depositing the eggs separately within cracks and crannies in the bark of ash trees. The eggs of the emerald ash borers begin as a whitish color, but change to a yellowish brown just before they hatch; about one to two weeks after the eggs are laid.
The larvae begin life tiny and white, and begin boring through the bark of the ash tree immediately after hatching. They make their way to the cabrium; a nutritious layer of the ash that lies between the bark and the actual wood of the tree. They will remain as larvae, continually chewing away at the tree’s tissue, for up to two years. Meandering through the cabrium, an “S” shaped pattern will be formed as the emerald ash borers eat. Four instars will be completed by the larvae; growing larger in each stage until they reach a length of approximately 1 to 1 ¼ inches. After entering pupa stage in the spring, the adult emerald ash borers emerge in early June; staying with ½ mile of their point of origin as they search for mates to begin the life cycle once again.
Emerald ash borers are an invasive species that are continually being monitored in order to eradicate them before more damage is done. Any evidence of their presence should be immediately reported to the county extension office for professional intervention of this destructive beetle.