It’s the worst feeling for a homeowner who takes great pride in their landscaping. You notice that your trees are showing signs of decline. They don’t look very healthy, they are growing sporadically and have uneven growth. A closer look shows disturbing signs of beetle-like creatures that have invaded the trees. It’s very possible that your trees have been attacked by borers.
Wood-boring insects are some of the most destructive pests of ornamental trees and shrubs. Borers are the larvae of certain types of moths and beetles. Small, they may be, but don’t underestimate the damage they can do. Since borers tunnel and feed under the bark of trees, they work their way from the inside out, destroying vascular tissue. Borer infestation also weakens trees, making them more susceptible to disease and infestation. Additionally, since the borers are protected under the bark, conventional pest control method are often less effective.
Signs and Symptoms of a Borer Attack
The signs and symptoms of a borer attack are similar to other types of pest or disease infestations. That’s why it’s important to look for a combination of symptoms to correctly identify if your trees have been attacked by borers. Symptoms of a borer infestation include the following:
Crown dieback – Dieback of the upper and outer crown from borers feeding on the trees. Trees start to show dead branches at the top of the canopy since the larvae disrupt nutrients and water to the upper canopy. The leaves then look discolored and thin, and without a strong canopy with leaves to provide nutrients to the root system, the tree can quickly make a turn for the worst.
Epicormic sprouting – When trees are stressed, sick or weakened, they start to grow in sporadic ways so that they can produce as much energy while they still can. You may notice that your trees have new growth at the bottom of the tree and trunk, below the borers that are feasting on the tree.
Bark splits – If you notice vertical splits in the bark, this may be a sign of an infestation since the borers create callus tissue. This tissue develops around the larvae, which can often be seen beneath the bark splits.
D-shaped emergence holes – When the adults emerge from the bark of the tree, they leave behind D-shaped holes that are about ⅛ inch in diameter. These holes mean that borers have been living under the bark long enough for them to be mature adults.
S-shaped larval galleries – When the borers feed underneath the bark, the move back and forth in an S shape. These galleries are filled with larvae poop and sawdust.
What Happens Next
Unless you are looking for borers, it’s hard to tell that they are there. If you notice at least two of the above symptoms, it’s very likely that your trees have been attacked by borers and you need to act quickly. To verify, look for larvae that are cream colored and slightly flattened. They will be found feeding beneath the bark. The adults mature in June and are metallic green, flat on the back and about the size of a grain of rice.
If it’s true that your trees are under attack, contact a Certified Arborist immediately. Borers are some of the most destructive pests, and it takes a professional to know what types of treatment will work best for the infestation. Bark sprays can prove beneficial when used at the appropriate time. In the meantime, make sure that you keep your trees as healthy as possible, as borers are more likely to attack vulnerable trees. http://growearthtrees.wpengine.com/borers/