How to Kill Carpenter Ants in a Tree

By Laura Hageman

Carpenter ants are black and red and live in rotting, moist wood in trees and houses. These ants do not eat the wood they live in. They eat protein, sugar, and other types of insects, dead or alive. When you see carpenter ants, you may assume they are destroying the wood. However, carpenter ants are actually infesting an area that is already ruined. They make tunnels throughout the wood to travel back and forth, which will leave behind evidence of carpenter ants with small shavings of wood at the bottom of the area they are infesting.

carpenter ants on a decaying tree

Step 1

Locate the carpenter ant colony in the tree. Analyze where the carpenter ants enter their colony to determine the entrance of the colony.

Step 2

Apply a dust or liquid insecticide. Spread the dust insecticide around the entrance of the colony. Spray the rotting tree with liquid insecticide, starting at the bottom of the tree and working your way up the trunk. This could take up to two weeks to be effective and kill most, if not all of the carpenter ants.

Step 3

Place bait systems around the rotting tree as an alternative method to killing carpenter ants in a tree. There are two kinds of bait systems that can be used to kill carpenter ants, plastic bait stations and ant stakes. These bait systems will need to be checked weekly since they can dry up rather quickly and need to be replaced. The bait system could take up to several weeks before it is completely effective, killing all of the carpenter ants.

Step 4

Remove the rotting tree. Digging out the tree will prevent new carpenter ants from re-infesting the tree. Check other trees nearby to make sure they are not rotting away. Remove them if they are rotting.