Comes under the "all sources, one destination" category apparently. Usefully this article specifically covers this technique for making a tower defence game. It's obviously not using Construct, but he explains the concept as opposed to showing code so it should doable.
You want to produce a "vector field" for your ants to follow.
Yes, I was analyzing a bit more the video there is a moment of the video where you can see some lines, apparently it is where the ants move and this line is painted blue, establishing a diameter that tells the ants that there is a cave, but on the other side the diameter is painted yellow.
What I could deduce is that the ants inside the diameter detect the coordinate where the food is and when having a piece of food their destination is the coordinate where the cave is, basically it is as said plinkie, it is a Pathfinding, since the Pathfinding is Handles by 16x16 grids in its natural state.
Reviewing the article that you sent me from Red Blob Games, I see that your example has the same behavior as Pathfinding, when frontiers are redrawn, and doing some tests today with Pathfinding, I could do that in real time while traveling the subject from point A to point B if you place an object recalculates the route to point B without establishing a cut in its route, this is achieved only with an object.