I had begun to hope that this year, our annual carpenter ant invasion might be curtailed somewhat. However, a few days ago I began to hear the telltale patter of teeny tiny feet next to my ear as I sit at my table/writing desk. The ants have started spreading out into the walls. I can hear them when they walk on the plastic sheeting that encases the wall’s insulation by my head. It’s not bad—yet—but it’s definitely time to take action.
A few years ago, I ended a post on this subject with a somewhat philosophical, “live and let live” comment (see Living With Carpenter Ants). Yeah, well, forget all that—sometimes, like when they start messing around in the walls, you’ve got to execute with extreme prejudice! Here’s how we control carpenter ants with homemade bait:
Borax, the old Twenty Mule Team stuff, makes a very safe ant killer. The trick is to get the ants to eat it. We do that by mixing it with food, but it has to be the right food. If you get it right, they’ll carry it back to the nest, feed it to nest mates and the queen, and they all die.
It seems like a no-brainer. Aren’t carpenter ants, like all ants, attracted to sweets? The answer turns out to be: not really. Carpenter ants will eat sweets, but they’d rather have proteins.
We proved this a few years ago by mixing borax into powdered milk, and with sugar, about equal parts each. We sprinkled both around our problem areas. The sugar and borax went almost completely ignored, but the powdered milk and borax quickly disappeared. So too, did the ants! Within about a week the noise in the walls ended. The main nests outside were bigger and deeper, and took longer to eradicate, but the ones closest to the cabin weakened and died. For that year, anyway. The ants always seem to return eventually, as they have recently.
If you Google homemade carpenter ant bait you’ll find a lot of warnings against using borax. Don’t be concerned. These writers are apparently confusing borax with boric acid. Borax seems to be safe, but one can make boric acid from borax. Boric acid can harm your pets, but borax appears to be safe to use around them. Although, I love pets—if I found a domestic animal lapping up our homemade carpenter ant bait, I’d definitely consult a veterinarian immediately, just to be safe!