Emerald Ash Borer
The Emerald Ash Borer (EAB) is a non-native, highly destructive wood-boring beetle that feeds under the bark of ash trees. All species of ash are susceptible to attack, except mountain ash, which is not a true ash species. Since it was first identified in Michigan in 2002, the EAB has killed millions of ash trees in Ontario and many parts of the United States. It poses a major economic and environmental threat to urban and forested areas. It was confirmed in Ottawa in 2008 and its impacts can be clearly seen spreading from the St. Laurent area. Since the insect spends most of its lifecycle under the bark of trees, it can be easily moved with firewood or other tree materials such as nursery stock, logs, brush and larger wood chips. This insect is able to fly, but since its spread has been primarily along major highways and transport routes, it is clear that humans are the main vector of dispersal.
The Tree Disease
Top branches of ash trees usually die off first. Trees can lose half of their branches in a single year. Once larvae finish feeding under the bark, they mature into adult beetles that chew their way out of the tree.
Signs of the EAB:
- loss of leaves and dead branches in the upper part of ash trees
- unusually thin tree crowns
- branch and leaf growth in the lower part of the stem where growth was not present before
- unusually high woodpecker activity
- bark splitting
- S-shaped grooves beneath the bark caused by larval feeding
- D-shaped exit holes 3.5 – 4 mm wide caused by adult beetles
Infested ash trees in North America generally die after two to three years, but heavily infested trees have been observed to die after one year.