The Emerald Ash Borer beetle has caused damage to ash trees in North America over the last decade or so, and it’s still kind of a mystery as to what exactly this beetle is. If you’re curious about how this beetle got here, what it does and how to spot it then here is some more information about these shiny green bugs.
Where did it come from?
Around 2002, the Emerald Ash Borer migrated from Asia to North America. It feeds on ash trees which are commonly used in landscaping across North America, but especially in South Western Ontario. Via the movement of ash-based products, it is likely that this beetle will continue to migrate further across North America.
What does it look like?
Once an Emerald Ash Borer has matured it will have a shiny emerald-green or coppery-green body with large, kidney shaped eyes that are usually black in colour. The body of it is fairly narrow, and will often be about 7 or 8 mm long. The adults can typically been seen around trees from early June to the end of August, feeding on the leaves of ash trees.
How do they spread?
As the female beetles are eating through the leaves of trees, they will also deposit eggs into the crevices of bark on these trees or under the bark scales. The larvae for these beetles will hatch and develop on the inner part of a tree, and they will then chew their way out of the tree when ready.
The eggs are often hard to detect because they are so small, and are often hidden under the bark of a tree. Freshly laid eggs will be a creamy, yellow colour whereas eggs that have been laid for a while will be a more red-brown colour, like rust.
How do they hurt trees?
The eggs are laid under the bark of a tree, and eventually these eggs will develop into larva that is about 30 mm long. Depending on the infestation level of the tree, there could be hundreds or even thousands of larvae in a single tree. The larvae essentially feed off the tree by absorbing the nutrients under the bark. In doing so, the flow of nutrients the tree needs to survive are cut off and this can kill the tree. The majority of the development of the larvae happens over the winter when the tree has already lost a lot of its leaves so it can be harder to tell if a tree is infected when it isn’t blooming.
If you are in an area that has been affected, or could be affected, by this bug then it’s important to keep an eye on the trees on your property. Checking for things like premature loss of foliage and cracks in branches could be a sign of an infestation of this beetle. Typically municipalities will issue warnings to the public when these bugs have been found to be specifically active, so keep an eye out for notices.