My homemade remedy didn’t last long. The ants got back into the kitchen Friday while I was at work.
Saturday morning, I spent about fifteen minutes outside, antwatching. Trying to figure out where their anthill was. I never did quite find it, but I figured out the general area, and started spraying (with the bug spray that the previous owners didn’t take with them when they moved out).
Wow, it worked. That particular ant colony now consists only of the few ants that were already in the kitchen, and never quite managed to find their way back out through the dish-soap gauntlet. I saw (and smushed) one straggler this afternoon, and otherwise none since yesterday.
Man (or rather, man’s consumer chemical industry) triumphs versus insect. It’s a small victory, but hey, you take what you can get.