[Hot Tabasco]

spray em with black Krylon. When they go back inside and see they are all black, they’ll stop working and start killing each other.

[Purdue77]

When I lived in VA, I watched two diverse ant colonies meet on an ant trail. Apparently, they didn’t like one another. The battle ensued, but I didn’t have the time to see which one won. When I returned ant carcasses littered the trail.