Ants on the March

The ants have come out in force. Weather maps at COLA IGES suggest southern California will have some drying over the next week. Coincidence? Perhaps the ants sense that spring is on the way.

This is the first house I’ve ever lived in built on a slab and without any crawlspace under the floor. During the spring, summer, and fall, the ants routinely invade from any minute stucco crack or other entrance they can find. Sometimes, this creates quite an emergency in the kitchen, as we attempt to find what entrance they’re using, and then clean their in-the-house tracks with vinegar (which dissolves the pheromone they leave behind in their trail so other ants can follow them). Once I’ve located where they enter the house, in the past I’ve sprayed poison around that outside entrance and along and on the vertical concrete foundation.

This year, rather than spraying poison around the outside foundation, which is always a short-term and temporary fix, this year I’m trying something new. Bait the ants, in the hope they’ll take the poison back to their nest and share the food, especially with their larvae. I’m only concerned with the ants that are near the house, the ones that repeatedly invade.

Last year I ran accross the following Texas cooperative extension pdf, prepared by Bastiaan M. Drees. He describes a mint-jelly bait recipe with 1-2% boric acid added. I’ve seen other recipes on the Internet with boric acid amounts up to 50%. The professor claims that a 1-2% mixture is just as deadly for them, but that they can detect more concentrated amounts and thus will avoid those baits. Further, he writes, a reduction in the colony’s numbers is only accomplished after 2-3 weeks, so this treatment should be started early in the year when the ants first start swarming and breeding. Once the nest becomes well enough established after the intial spring breeding, it’s not as effective to then begin baiting them. Apparantly the boric acid slowly dissolves the ant’s digestive system. Boric acid can be obtained at most pharmacies as an OTC product.

Another interesting read by the same author is a pdf titled “House Infesting Ants and their Management.”

I’ve noticed in the past few years the Argentine ants we have a problem with are attracted to the honey jar on the kitchen counter, so I’ll mix Professor Drees boric acid bait with honey, and I’ll leave the bait outside along their tracks next to the house foundation.

1% boric acid/honey recipe: 1 cup honey 1/2 teaspoon boric acid

I’ve found that after combining these two ingredients, the powdered acid doesn’t mix well. The best way I’ve found to dissolve it is to heat the mixture until it’s quite hot, then stir. I use the microwave oven.

We’ll see if this works this year to reduce the ant population. Yesterday I placed the bait near their tracks, and they’re swarming over and around it. They were feasting everytime I checked them last night, well after sundown. I thought that was unusual. In prior years, they only seem to be on the march during the day. In any case, I do hope they get their new-found bounty back to their nest, their larvae, and their queen(s).


On the day I published this, it’s now been 3 days since starting this regimen, and it’s going to be rather difficult for me to be patient enough to test the whole 3-week window. I already hear my mind telling me it’s not working. I guess I’m used to the instant effect of traditional pesticides.

Feb 28: The ant tracks near the bait do indeed seem less populous, could it be working this soon?


As I was writing this, I realized there’s an analogy between swarming ants and spammers. Spambots? Spammants? Spamswarm?