Found where the ants were getting in, and it was not where I thought

Last Saturday I pulled everything out of the pantry to wipe the shelves down, and that is when I spotted a thin trail of ants running up the outside of my water heater closet in the hallway. I figured they were coming from the kitchen since that is where I kept seeing them, but they were actually marching down from the attic through a gap where an old cable comes out of the wall plate. I sealed that gap with a little steel wool and caulk for about $8 and the ants in the kitchen slowed down within two days. Turns out they were using my pantry as a second stop, not the start. Has anyone else chased ants to the wall plate like this, or am I the only one who checked the kitchen five times first?