The borers are usually divided into roundhead and flathead types. The native borer insects are part of Nature's plan to recycle trees since they attack weakened, stressed trees and generally do not bother sound, vigorous trees.

Unfortunately some of the imported i.e. exotic, borers such as the Emerald ash borer or the Asian longhorn beetle infest both vigorous, younger trees and older stressed ones. Bronze birch borers generally attack trees that are weakened by the birch leaf miner.

Often, the first sign that the home gardener notices about an infestation of borer insects is their randomly spaced exit holes. It is the larval form of the insect that does the boring in the wood as they grow. When they turn into adults, they burrow their way out and leave the hole behind. The holes may be from to inch in diameter depending on the species of borer.

***Note: If the holes are in a straight line, the problem is either woodpeckers or sapsucker.

About the only way to prevent native borers is to keep your trees as healthy as possible by watering during droughts, allowing enough room for trees to spread out and pruning properly.

Other measures have been taken to prevent the Emerald ash borer and the Asian longhorn beetle, which, as mentioned above, attack healthy trees too.

For our native borers, once they infest a tree, it is probably too late to control them. The real problem is often that the tree is in general decline because of age or "shade tree decline" and the borers are just part of the process of returning them to the earth.

Chemical treatment may be appropriate in some cases but it would have to be applied to the bark to prevent the adult borer from laying her eggs. Once the borer is inside the tree, there is not much you can do about it.

** Again, the exceptions to the rule are the Emerald ash borer and Asian longhorn beetle.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

Types of Insects

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