How do you get rid of ants? I have found that people use 3 common home remedies to get rid of ants; diatomaceous earth, Borax and coffee grounds. Borax does work and it is the main ingredient in many commercial products designed to get rid of ants. In this post I will look at the effectiveness of coffee grounds.
Why get rid of Ants?
Before I get into the main topic I would like to make a comment about ants. They are very good for the garden since they improve soil structure. Sometimes they build their nest right under a precious plant and that may cause a problem–but they rarely harm a plant. Ants are predators and eat other insects, so they keep bugs from eating your plants. For the most part their ant hills can be tolerated.
Ants in the home is a different story. I understand why you would want to get rid of them in the home.
But if they are in the garden, try to learn to live with them and leave them alone.
Ants and Coffee Grounds
You will find this advice all over the internet. If you want to get rid of ants, put coffee grounds on the ant hill and they will leave. Sounds simple enough. I searched the internet for some scientific evidence that coffee grounds actually work to get rid of ants and found none, so I decided to run some tests. My testing is not very scientific but it does give some insight into the issue.
Ants, Coffee Grounds and the Shed
I built a garden shed about 8 years ago. Almost from day 1, ants took up residence in the shed. There is a space between the two header beams across the main 6 foot wide door. In this space they are well protected, and unfortunately, the way I built it, I can’t easily get at them. I never really tried to get rid of them–they don’t harm anything.
The common advice for using coffee grounds is to put them right on the ant hill, but these ants don’t have a hill. So I tried to put some into the space where they live, and I smeared coffee grounds along the trail they use for getting into and out of their nest. I then watched.
The ants sure don’t like coffee grounds. They would walk up to them, turn around and go back the way they came. That looked very promising, but would this be enough for them to leave the shed?
The next day I came back to see how things were progressing. The ants had pushed the coffee grounds off their path, and life was back to normal. I think I heard one of them squeek “that was a fun diversion for a few hours”.
Ants, Coffee Grounds and the Patio
I have a patio made out of rectangular man-made stones which are sitting on sand. From day 1, ants moved in and live under the stones. I found two entrances to their home, which were quite close together–probably led to the same nest.
One of the openings was just a hole between the stones. Ants were busily coming and going from the hole so I decided to surround the hole with quite a bit of coffee grounds, making a full circle. Ants the came out of the hole, walked up to the grounds, and then went back under ground. Ants arriving from distant lands went up to the coffee grounds, stopped, turned around and went away.
The second entrance consisted of a hill of sand which the ants had excavated. Many ants were busy going and coming using this entrance. I covered the hill with coffee grounds, making sure some sat right in the entrance hole. Same as before, ants would not cross the coffee grounds.
Things looked very promising. Ants clearly do not like the grounds. It could be the smell, or it could be the particles themselves. I was dealing with small ants and the grounds were almost as tall as the ants.
Around noon the next day I returned to the ant hill. All was quiet–no ants. But then I noticed that ants at other untreated hills were also gone–WOW this stuff really works. I came back later in the day to check on things only to find that all the ants were out working again. I guess they took a lunch break during the hottest part of the day. Once things cooled down they were back.
What about the covered ant hill? They had removed almost all of the grounds from the hill and they were back in business. They did abandon the hole that was surrounded with grounds, and made a new entrance almost beside it.
Ants, Coffee Grounds and Precious Plants
I have a new rock garden full of very small plants and I look at it almost every day. Suddenly one day, one of my prized possessions looked like it was dying. I gave the plant a flick of the finger, and a bunch of ants came scurrying out. They were building a nest right under the plant, and since the plant was only 2 inches wide, they were doing quite a bit of damage.
I ran for the coffee grounds and spread them thickly around the plant. By this time I did not have too much confidence in the stuff, so I also got some Borax + sugar, and shook it over the plant itself. By the next day the ants were gone.
I don’t know if it was the coffee grounds or the Borax, which does work, but not that quickly or maybe it was my fingers shaking the plant. It is very likely that the ants were just starting to build their nest and decided to go somewhere else which was less hostile.
Ants and Coffee Grounds–Conclusion
It is clear that ants do not like coffee grounds, but they don’t seem to mind the coffee itself. When I was applying the grounds some of the coffee also spilled onto the patio stones and they just walked all over it. I also don’t think it is the smell since ants walk right up to the grounds, before turning back. If the smell bothered them, they would turn around sooner.
I suspect that the grounds are just very large in comparison to their size–they are a physical obstacle for the ant. Keep in mind my tests were done with small ants. There are thousands of different ants, and another type might behave quite differently.
Based on my observations, ants don’t like coffee grounds, but they don’t create a major problem for them. They will go around them, ignore them or just move them out of the way. Since I monitor the rock garden closely, I am quite sure the ants had not been there for long, and I am guessing that in the case of the small plant, they had not yet made much investment into their home–so it was easier to move on than to fight me and the grounds.
Unless someone can provide better evidence, I must conclude that coffee grounds are not a good way to get rid of the type of ants I have in my garden.
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