Carpenter Ants in Trees – Are They Harmful?

With carpenter ants out in full force, our arborists have been getting a lot of questions about these insects and if they are dangerous to trees. Surprisingly to most homeowners, Carpenter Ants themselves don’t damage trees. Instead, they are an indicator of dead wood, cavities, and other decay in your tree.

Carpenter Ants take advantage of existing decay situations. They build their nests in wet and rotting wood and generally never extend into the healthy parts of the tree. Decay situations are commonly created by stress, mechanical injury, environmental conditions, disease or other insects. Decaying limbs and branches are also more common in mature trees, which is why you will most likely see carpenter ants on your older trees.


How To Tell If They Are Carpenter Ants Or Just Normal Black Ants?

  • Carpenter ants can be black, brown, red, or a combination of the three.
  • Carpenter ants are generally much larger than regular black ants. Carpenter Ants range from ¼ inch long to ¾ inch long compared to black ants that are typically less than 1/4 inch.
  • Carpenter ants have a head that’s shaped like a heart rather than a circle.
  • Some Carpenter Ants (reproductive females and males – called swarmers) have wings.
  • Carpenter Ants will have piles of wood shavings can be found on/around the tree. This comes from them tunneling into the decayed part of the tree.

If you have normal ants all over your tree, you most likely have a plant sucking insect problem which is excreting honeydew (looks like sap dripping from tree). Normal ants love to feed on this sticky substance. Learn More About Honeydew & Plant Sucking Insects.

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Treatment for Carpenter Ants in Trees:


  • Insecticides to control the carpenter ants are not advised since these ants do not cause damage to the tree.
  • Plugging or sealing tree cavities or dressing wounds is also not advised. This is an outdated procedure and can make the tree’s health decline even faster.


  • Tree pruning to remove deadwood. Typically pruning out the decaying limb(s) where the ants are nesting.
  • Make sure the tree is well watered but not overwatered. This will reduce drought and flood stress. Check out our watering tips.
  • Bio-Stimulants to stimulate health and root growth boosting the immune system of the tree.
  • Treat any other insect or disease that is affecting the tree. This will reduce further decay and stress.

If you have carpenter ants on your tree it’s best to have an arborist evaluate the health of your tree and check for decay. Extensive decay can make your tree hazardous so it’s important to regularly evaluate decay and remove decaying limbs.

0 thoughts on “Carpenter Ants in Trees – Are They Harmful?”

  1. Afton Jackson says:

    It was quite alarming to read just how similar carpenter ants are to termites. At first, I didn’t think much of them when I saw them around the trees near our house, but learning this has really made me worry since my house has a lot of wooden fixtures. I’ll make it a point to start looking for an ant control service right away so they can exterminate those carpenter ants before they do any damage to my house.

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