Easy DIY method for getting rid of a carpenter ant infection inside the home without the use of chemicals or other toxic substances.
We’ve had two major infestations of carpenter ants to deal with during the 25+ years of living in our home.
The first occurred shortly after we moved in. Our house was built in 1951 and sits in a semi-rural neighborhood with lots of trees, vegetation, and moisture due to a backyard lake. Needless to say, it is the perfect environment for critters of all kinds including carpenter ants.
The first infestation had me calling the pest control company in a hurry!
Calling Pest Control for Carpenter Ants?
Carpenter ants are huge and very scary looking as you can see from the picture above. While they do sometimes bite, there isn’t any poison, so if you are careful, you can pick them up with your fingers and throw them in the toilet or flush down the drain with no problem.
At the time, though, I didn’t know any of this, so seeing dozens of large ants running around my then retro style 1970’s orange and yellow kitchen was not a pretty sight.
I picked up the phone and called pest control and after a couple of toxic sprayings around our house, yard, and then in our attic over the course of a week or two, the carpenter ants were gone.
The Natural Approach is Very Effective
Our second infestation of carpenter ants happened just a few weeks ago, and this time, I handled it very differently.
Having the knowledge and wisdom of 20 years of green living behind me, I was determined and very confident I could resolve this infestation with zero pesticides and no call to pest control.
My youngest was especially freaked out by the enormous size of the carpenter ants even after I explained that they don’t have a sting like other types of ants and picked up one in my fingers to show her. Unfortunately, my little pep talk and demonstration didn’t do much to alleviate her fears of these intimidating, wriggling creatures.
The carpenter ants were swarming in our kitchen and bathrooms and after starting with just one or two here and there, over the course of a week, they came in by the dozens overnight while we slept making for a very scary turning on of the lights in the morning if you know what I mean. We spent the first 15 minutes of the morning vacuuming them up before we could even get started with breakfast!
Find Where The Ants are Trailing
After watching and observing their patterns over the course of a day or two, I determined that their primary mode of entrance into our home appeared to be the drain of the dishwasher.
Knowing where the carpenter ants are getting into the house is a helpful piece of information, but not entirely necessary if you wish to eradicate them yourself via nontoxic measures.
In our case, the dishwasher drain seemed a likely ground zero, so I mixed up my carpenter ant killer ambrosia and set the bait.
How to Mix Nontoxic Bait
My one cup of ant bait consisted of the following all of which cost less than $1. Believe it or not, this is all that was needed to get rid of ants quickly and easily.
- 1/3 cup of powdered white sugar
- 2/3 cup boric acid (where to find)
That’s it!
Note: you may use borax powder for a less strong mixture.
When I took our container of boric acid out of the garage utility cabinet, it consisted of a bunch of hardened chunks that needed to be pounded out as I hadn’t used it in a long time.  So, I took out my mortar and pestle and pounded out a few big chunks to re-powderize and then measured it into a small ziplock bag that contained the appropriate amount of powdered sugar.
Boric acid is a colorless white powder that is a mild antiseptic, but certainly not a problem to the health of your family even if you touch it with ungloved hands. It is found in nature in some volcanic environments near Tuscany and Nevada.  Boric acid and its salts are found in seawater and plants including almost all fruits.
Keep Away from Pets and Children
Of course, you need to keep it away from small children and pets. It is poisonous if ingested or inhaled in large quantities.
However, it is probably the least toxic form of insect bait you can use around your home. The one exception is diatomaceous earth, which unfortunately doesn’t work as well or as quickly for large ants where I live.
Where to Place the Bait
I placed a couple of tablespoons of the carpenter ant bait in the lid of an empty jar I was going to recycle and placed inside the dishwasher on the bottom near the drain just before going to bed.  Before I did this, however, I was careful to run a load of dishes and empty everything out so the dishwasher was completely void of any plates, glasses, or utensils.
A Happy Ending to our Carpenter Ant Infestation
The next morning we were delighted to see that there were no carpenter ants running around the kitchen! Â When I opened the dishwasher to have a peek, they were swarming around the bait but were totally confined to that area.
I gently closed the door of the dishwasher and left the ants there, happily eating away at the bait they would take back to their nest to kill the whole colony.
It took a few days, but gradually, the carpenter ants swarming inside the dishwasher completely disappeared with nary a stray one left!
When I needed to run the dishwasher in the interim, I simply removed the container of bait, ran a load, emptied the clean dishes, and then replaced the bait near the dishwasher drain.
Simple, effective, non-toxic, and best of all, cheap with no call to pest control to come and spray who-knows-what hormone-disrupting, carcinogenic chemicals around your home for your family to breath and absorb!
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But how were they getting into the plumbing? That’s freaky. Maybe a call to the plumber is in order.
We have a septic tank 🙂
They DO bite and hurts! When we moved into our home we had a huge nest in the living room wall. My son was helping me vacuum them up, one got on his finger and actually drew blood. Pest control said they’ll bite to defend their nest so maybe if the nest isn’t established, they’re a little more peaceable. I love the recipe! Sounds like a plan for spring when they try to build their living room wall nest AGAIN. Grrr.
I make a slight variation to the recipe: 1 cup sugar, 1 cup boric acid, 1 egg, just enough water to mix to a cookie like dough, spread out in foil covered pan and cook at 350 degrees for 10 minutes. Cut into small squares. Place around house. It will kill every roach in your house, I don’t care how big or how many! I know! I haven’t tried it for ants but I’m sure it will work for them too. The egg puts just enough fat in the mixture to attract fat loving critters, the sugar puts just enough sweetening to attract sweet loving critters, the boric acid KILLS them. Be sure to keep away from pets. Boric acid and arthritis, search engine. It will amaze you.
Thanks Sarah.
I’ve used this idea before with corn syrup instead of powdered sugar. It hardened and the ants would go under it (fire ants). This sounds way less messy, so I’ll try it this summer when the ants find there way in again.
Wow. Was just telling a friend I needs natural ant killer. My garden grow pots are overrun with fire ants. Will try this. Any experience with them? I live in south FL.
Dirtdoctor.com, organic gardener, says do not use boric acid outdoors. It gets into the ground water. Use indoors for anything that crawls. The powder can be placed under the fridge so is away from kids and pets. The insects crawl through it, travel back to their nest. The queen grooms them and gets the boric acid which kills her. For sugar ants, mix with corn syrup or just put some sugar and boric acid on a piece of paper to slip under the appliances. Easy to pick up and throw in the trash bag.
Greats, I have a problem with weavils, don’t mind the spelling, these pest get in cereal, flour and some spices like dill, any suggestions “please I need help they are costing me a pretty penny. Thank you.
Many food insect pests are in the food when you buy it. You could be buying old stock. Many of these pests are killed by freezing so put new purchases in the freezer for at least two days. These pests are nocturnal and come out at night to crawl slowly into the food so close up the packages with rubberbands or clips or transfer to jars. However, cupboard moths lay eggs near jar tops and the larvae can crawl around the jar threads to get into the food. If you see a cupboard moth, smash it or get the sticky traps.
THANK YOU!!! I have always used boric acid mixed in honey for the little black sugar ants but it’s always hard to clean up after. It does work but the powdered sugar is awesome!!! Wow – why didn’t I think of that!! Oh, well, I’m armed now for summer! Thanks!
Interestingly I tried the borax/sugar solution and while they work fine for other types of ants, the carpenter ants where we live were totally (I mean TOTALLY) uninterested in it, they pretty much just ignored it. We had to spray the toxic stuff unfortunately, but fortunately it was all exterior so we didn’t have to breathe in the toxic stuff. For inside the house DE has always worked great for us (I prefer that to the borax, since we have small kids).
Did you use borax or boric acid?
Boric acid.
We had a major infestation over the last two years. We live in an Insulated Concrete Form home, Apparently, something in the Styrofoam insulation mimics the smell of the queen ant’s hormone,. After LOTS of research, we tried countless natural repellents and poisons… and then a toxic one or two. NOTHING worked. Finally, one night they got so bad that, in the most infested room, every other step left me crunching the biggest ants we’d ever seen. My husband and I searched high and low until we found their hole and then we stuffed it with diatomaceous earth, DE. IT WORKED, oh man, did it work! Within two days there were no more ants! YEAH! Cheap and natural! So maybe there’s two natural options that work!
I will try this, I have been infested with thousands of odorous ants for 2 years. Had to move out when my bed was full of ants. I have used many traps from the hardware store, borax on a regular basis & every other idea that comes across the net & finally poison granules. They disappear for a week or so then they are back in force.
For boric acid use, some ants prefer grease. Real potato chips with boric acid on a piece of office paper got the ants that crawled up the tree, along the roof, down the wall, across the living room and under the desk to bite my son who was eating in the wrong place!
As with all these things, you cannot expect instant eradication. You must wait for the boric acid to get to the queen and maybe the next one they are preparing so it can take some days.
Great tip! Cinnamon works to deter ants, but you have to put it where they are crawling (so you may not be able to hide it like you did with the dishwasher). I put some across the threshold of our back door and the ants stopped coming after a couple of days. The only thing is that it doesn’t poison them like your solution does.
Cinnamon does deter them but won’t kill the nest which is what is ultimately necessary to get rid of carpenter ants.
Absolutely. Thanks for sharing this recipe!