Unless the ants have built their anthill directly under a plant so that the plant roots are disturbed, they are not harming anything. If they do have the anthill under the plant you would see mounds and ants above ground.

It is difficult to kill ants that are living outdoors, as there are millions and millions of other ants around to take their place. If you really think you need to kill them (remember, they are doing no harm), you can buy an inexpensive commercial liquid solution of borax and sugar that you dribble near the anthill. The ants take it into their hill and feed it to the other ants which eventually all die.

I sprinkled cinnamon on an ant hill that was by my pond. The ants packed up and moved somewhere else. I had tried all kinds of other things but this is what worked for me.

Danni

Thanks for that idea, Danni - i'm going to try it! We have all kinds of ants in the yard and they do seem to cause damage to the plants by taking soil away from the root area. I've lost a few things that way.