This might be more of a summer post, but with spring around the corner (not that you’d know it from looking out my window, where the view is snowy), I thought it was worth sharing.
After about two years in our house my wife and I noticed ants wandering in. We’ve had the occasional carpenter ant scout on and off—they’re difficult to control since they can come from a pretty good distance away and I have no idea where their home turf is—but I’m talking invasions. Ants were setting up shop too close to the house, with nests just outside, and coming in.
The first two years, they were in our living room (mostly), coming in through the front door we never use. These ants were small, and very mildly aggressive (they would occasionally bite, but not frequently), but they only tended to show up in late summer through early fall, and they could be contained with traps. Specifically, we used the Raid Double Control ant bait traps that have abamectin as their active ingredient. This would cause the ant problem to slowly diminish and then disappear, though it could reappear in about a month or so, necessitating fresh traps.
In the second invasion year, though, we had another enemy. A colony had taken root just outside our side door, and was coming into our entryway and our kitchen. This breed of ant was different: They were slightly bigger, less aggressive, but way more apt to swarm. After the appearance of just a few scouts, the kitchen was overwhelmed in short order. These ants laughed off the Raid baits. We decided emergency action was called for.
After doing some research on DIY controls, we found something that was supposed to work: borax. Several kinds of ant control use boric acid, which is a cousin of alkaline borax and believed to be more toxic. We looked up toxicity because we were concerned about our cats; the research suggested keeping the stuff away from cats and that it could be bad for humans in large quantities. Everything I’ve read since suggests it’s boric acid that’s the real problem, and the mistaken interchangeable use of the terms has clouded a lot of the discussion; nevertheless people have been using borax in laundry and dish detergents for decades without problems, so I think it’s pretty safe. I’ve even found recipes for using borax to make homemade play slime for kids; supposedly the toxicity of this stuff is around the same level as salt or baking soda, meaning you’d have to ingest massive quantities to get in trouble.
That said, it’s probably best to keep this away from your pets and kids anyway.
It was late evening on a Sunday night when we had to act. I went to our local P&C grocery store (it’s a Tops now) and got a giant 4 lb. box of borax, because it’s not typically sold any other way. You’ll find it in the laundry soap aisle, and it’s used for all kinds of DIY detergents. Back at home, we mixed small amounts, scooped out with a little 1/8 tsp. measuring spoon, with about an equal amount of raspberry jam. Just stick both on a small piece of cardboard, and stir with a toothpick until the biggest chunks of borax have dissolved.
Since we had to get this in the ants’ path, we wanted this right between the vestibule and the kitchen. Our solution to protect the cats was to tape down the cardboard, and then we taped down a small plastic container over it using packing tape, but left just enough of the container sticking up off the floor to allow the ants access. When I went to the grocery store, I went to their stationery area and bought small packages of those pinchy clips used for big stacks of paper; they came in hard plastic shells with a lid and a base. The lid had tabs sticking down from the bottom which made it perfect as a roof for our bait, since the tabs propped it up. Later when we used the base as well, we just taped a tiny piece of cardboard to the inside to prop it up.
The ants went crazy for the raspberry jam in such a convenient spot. The kitchen invaders were decimated literally overnight. In about 12 hours there were only stunned stragglers. In 24 I saw a single ant, looking lost. After that they were no more.
Eventually we had another wave of these things later in the year, this time through the front door, displacing our previous invaders. Pulling the same trick at that door murdered the colony. We haven’t had those ants or their predecessors back since.
The only downside to this technique is that it’s not very well self-contained, and it could be a tempting target for very young children who might not understand what it’s for, or pets who might go at it. Again, I’m pretty sure borax is safe, but it’s not a good idea to tempt fate. We have cats, whose desire to go after the jam was about nil and their ability was even lower. A dog might be stupid enough to go after it but clever enough to use their tongue to get at it underneath the “lid”, so use caution.