How to Kill Ants Attacking an Oak Tree

If you are trying to kill ants attacking an oak tree, you should first understand that some ants are beneficial to the environment. They can help reduce populations of more harmful insects like ticks and beetles and may also aid in soil aeration and thus the growth of nearby seeds. That said, some ant species, like carpenter ants, can cause damage to homes, other structures, plants and trees. If you have an oak tree that is infested by ants, you may or may not wish to eradicate them.

Much of the time, the ants you see on an oak tree are carpenter ants. Carpenter ants are large and black or reddish; some also have wings. They often settle inside the cavities of an oak tree to establish their colonies.

Ants like these are attracted to older trees that have plenty of decayed or dead wood. In these cases, the wood is brittle and soft, which makes it easier for ants to infiltrate.

Carpenter ants are more likely to attack oak trees that are already stressed from disease, other insects and environmental conditions that cause wood decay. The weakened state of the tree is like a green light for the ants to move in. These insects do not actually eat the wood; they chew tunnels through it and produce sawdust called frass, which usually consists of discarded wood and dead insects.

If you think that ants are attacking your oak tree, look carefully at its base and use a rake to look into the dirt and any mulch surrounding the tree. Also, take a close look at the tree's bark. You may see the ants going in and out, so look for holes that are frayed around the edges as well as bark tunnels and sawdust. If there are any wood structures nearby, be sure to inspect those thoroughly.

It is more likely that the damage will be in moist areas, as this is what many ants like best. They could also be in nearby tree stumps, firewood and shaded locations near landscaping. Colonies can expand quickly, with tens of thousands of worker ants. The sooner you tackle this problem, the better.

You may be able to repel ants through the use of mint, lemon juice, cinnamon, black pepper or vinegar. All of these common household products can work to chase ants from your trees. However, if your infestation is more severe and ants have settled in the oak tree and established a colony, it is likely too late to attempt these natural methods.

There are certain insecticides that are made specifically for carpenter ants, and they come in dust (powder) and liquid forms. Whether you choose powder or liquid or simply make your own ant bait, the main objective is to kill the colony's queen, so once you have the insecticide, try to locate the ant nest. Look for a spot where a lot of them are exiting and entering the tree. If you don't see it right away, get a scraper and dig around the tree's base.

Powdered insecticides work well because once an ant touches the powder, it will poison the other ants with which it comes in contact. Reapply the powder after it has rained if necessary. Liquid carpenter ant insecticides must completely soak the nest as well as the tree trunk where the damage exists.

Some experts recommend ant baits, which can be put around the tree and on any ant trails that you see. This can prevent any satellite ant colonies that are beginning to form. As with any pesticide, make safety a priority before applying the chemicals and don't put them where kids or pets might play. Read the instructions on any insecticide thoroughly and do not eat, drink or smoke when applying it.