Ants immune to boric acid

OK, we’re having ant infestations in this house. They eat the regular boric-acid-based ant bait like candy and come back for more. First we tried a borate-based ant bait my landlord had (I forget the brand name) and then Raid Ant Gel (which doesn’t actually say what the active ingredient is, but I’m guessing it’s the same). In previous infestations, these were quite effective. These new guys aren’t fazed in the least. They really do just gobble it all up and keep coming.

So what is the solution? I’d really rather not spray insecticide around, at least not the nerve-agent type. The actual nests are outside or under the house somewhere anyway, so it’d be hard to make sure we got them. Any suggestions?

ETA: is it possible that the boric acid breaks down due to age? I wouldn’t expect that, but could be wrong.

Patience. Persistence.

I put out ant bait traps last year when ants swarmed my front porch. It took about a week before they disappeared. I think that the poison is slow acting so that the workers can survive long enough to carry the bait back to the queen and give her the poison.

You can get a Southern tamandua anteater. They are lovely animals.

You can also try a few of these

When ants become immune to boric acid the beginning of the end has begun.

Are you using a boric acid or borax bait? I use Terro brand- it has borax (sodium tetraborate decahydrate) in it. As others have said, you have to leave it there until the ants quit coming. This can take a few days.

If there are grooves or other low spots through which they come:
Spray 'N Wash does a lovely job of shutting them off. I suspect other such pre-soaks as well.
The enzyme apparently dissolves their muscle, leaving only the exoskeleton.

Sliding patio doors and some thresholds work.

One last tip: when you see just one or two: KILL THEM NOW! Those are the scouts.

Why? We are here to fight ignorance after all.

I deter ants with bay leaves and lemon juice.

Don’t use the bay leaves whole; crush them into a coarse powder and sprinkle on the ant trails along with some lemon juice. More info at:

Initially we used Terro. When that was gone, we switched to Raid Ant Gel, which as I said, does not say what the active ingredient is. Both had been opened at the time of the last infestation which was last year some time. Several months at least. So I was wondering if maybe the borax/boric acid goes bad (oxidizes) over time. This has been going on for over a week, now and they’re still coming.

We had two infestations last year. Both times it only took a couple days before they disappeared. And they didn’t even eat up all the bait we put out. This time, they eat it all up and then we put out more. Repeat several times.

I have been wondering the same thing about the ants in my house. I make my own boric/sugar solution and it was effective in years past, but last year they just seemed to eat it like candy and come back for more. This went on for months. One thing is that they had an alternative food source – a leaky drain in the wall that put water and food waste into the wall where they lived. Now they are back this spring and it’s time to make some more poison. At least it kept them all in the same place.

I’ve never had a problem in my house but there have been a couple times the ants have very visibly moved right on the threshold of my back door. That’s a little too close and I’ve standardized on a technique. Put a spoonful of smooth peanut butter in the corner of a plastic baggie and then add half a thimble of boric acid (available at the dollar store). Squeeze and pinch to mix thoroughly and cut off the tip of the corner to make a pastry icing bag. Since my problem was outside, I found out the hard way to put the bait into an occlusive container like a milk bottle cap or else the sun melts the peanut butter into a greasy stain. Watch with delight as the ants tuck in with vigor. They are gone in a few days.

If you use Dollar Store for chemicals which can degrade with time, it may be the chemical which has changed, not the ants.

In the case of bleach, the normal concentration is 6%. The dollar store version is 3%.
And yes, it does degrade in the bottle. Any chemical which can remove colors from fabric has to be somewhat reactive.
I use chlorine in a swimming pool. Whether I buy the bleach at 6% or the “Pool Chlorine” at 10% is simply a matter of arithmetic.
This is where buying at the big box store is better that the specialty store: the big box turns over stock quickly; the specialty store may not.

Boric acid works as a poison to ants and also it harms their exoskeleton, so ants would not be immune to the latter. Ants either like sweet or grease (fat) so you have to make sure you’re putting the right mix out.

You might also try diatomaceous earth (called DE). That works by cutting the insects (it works on anything with an exoskeleton) but it takes awhile. The thing to remember is to spread it very, very finely. If you put to much the bugs walk around it. They must walk through it. It works very well indoors and out, but it stops working when wet.

It’s very cheap to. You can order it in bulk through places like Ace or other hardware stores.