WHAT IS THE EMERALD ASH BORER (EAB)?
The EAB is an invasive species that feeds under the bark of ash trees and is currently destroying the ash tree population of North America. 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, 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.
EAB is one of the main reasons why Ottawa will be losing 25% of its tree cover in the next 3 to 5 years.
Emerald Ash Borers normally have a one-year life cycle, but some can take up to two years to mature. EAB lays eggs on tree bark and in bark crevices starting in late May.
EFFECT ON ASH TREES
In its larva form, which resembles a caterpillar, Emerald Ash Borer feeds just under the bark of ash trees. This feeding disrupts the tree’s circulation of water and nutrients. The presence of even a few insects in a tree can kill it.
Top branches of ash trees usually die off first. Trees can lose half its 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.
- 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
- look for bark splitting, S-shaped grooves beneath the bark caused by larval feeding, and 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.