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ambrosia beetle

Ambrosia Beetle; Signs, Symptoms, Prevention & Treatment

There are many species of Ambrosia Beetles currently found in the U.S. The Ambrosia Beetle is a small, cylindrical fungus farmer beetle approximately 2 mm in length that can be extremely damaging to your trees and landscaping. These beetles tunnel into trees (most commonly those that are dying or stressed) and create fungal gardens that serve as food for their larvae and the adults. This fungus then penetrates the plant’s xylem tissue, extracting nutrients from it.

ambrosia beetle saw dust coming out of tree trunk

Signs & Symptoms Your Tree Is infected With Ambrosia Beetles:

  • A dead giveaway that your tree has an Ambrosia Beetle problem is if you see toothpick-like frass tubes sticking out of the tree. However, seeing this is often rare because the “saw dust” is weak and is easily blown off the trunk.
  • So, a better indication is if you see saw dust frass around the base of your tree.
  • Ambrosia Beetle
    Ambrosia Beetle

    If you see the beetle (this is an obvious sign) – 1.4mm-4mm dark brown to black beetle

  • Dying of your tree evenly throughout. This could be a sign of many things and is often associated with root health or serious disease.
  • Holes about the size of pencil lead called “shotholes” at the base of twigs or throughout the trunk.

Prevention: It is important to understand that most species of the Ambrosia Beetle will only attack weak, dying, or dead trees. So, the most important prevention method is proactively caring for the trees on your property.

This includes things like:

  1. Regular inspection
  2. Watering properly
  3. Pest prevention treatments
  4. Calling an Arborist when you suspect a problem
  5. ambrosia beetle effects dead or dying trees
    This tree is planted way too deep. The first couple of rows of branches are literally below ground level and covered in sticky clay-like dirt.

    Ensuring that your trees are planted correctly. Here are some examples of improper planting:

    • Your tree is planted too deep and the first few rows of branches are below ground level.
    • Your tree is planted in sticky clay-like dirt.
    • Your tree is planted with the excessive use of black gardening cloth cover with a thick pile of needles and leaves layering this cloth making the base of the tree too wet and hot.

If your plant or tree begins to die, or becomes weakened for any reason, it will become much more susceptible to the Ambrosia Beetle.

Treatment: At Red Cedar, we spray the trunk with onyx to help treat your tree’s Ambrosia Beetle infestation. However, once infected, there is only a 50% chance of survival with this treatment.

ambrosia beetle attacks weakened trees
Holes where rodents were tunneling throughout, further damaging the roots.

In a recent case of Ambrosia Beetle infestation that we treated with onyx, we also found that the tree was planted way too deep, and rodents had been tunneling throughout which was likely damaging the roots. These two reasons, as well as some other planting mishaps, are likely the reason for the tree’s initial decline. Once the tree became weakened, it became susceptible and enticing to the Ambrosia Beetles. When our Arborist initially began to inspect this tree, it was assumed that it was likely dying due to some sort of root deficiency since the tree was dying evenly throughout. However, upon closer inspection, we identified small holes drilled throughout the tree’s trunk, leading us to our diagnosis of Ambrosia Beetle infestation, and our treatment of onyx spray.

How The Disease Spreads: The adult Ambrosia Beetle is most active in March, but they are active year-round. Females will create galleries within the first host plant or tree just beneath the bark where the eggs are laid. Females will mate with their brothers when they are newly hatched, and from there, move to another host tree. As the beetle attacks its host, they introduce vascular fungi that will eventually (likely) kill the tree. The effects can best be seen in mid to late summer after trees have been exposed to summer stress.

The health of your trees on your property is extremely important for many reasons. To avoid pest infestations that cause serious disease, prevention and proactive care is key. Red Cedar can help to ensure your trees are planted properly, they’re maintained correctly, they’re proactively treated to prevent pests, and that they are diagnosed and treated correctly if an issue does arise. Contact Red Cedar today for your free comprehensive consultation, and let us ensure the health of the trees on your property.