Outdoor Ant Baiting Tips
The best way to control the outdoor ant population is always to kill the entire colony at the core. You want to be able to locate where the ants are coming from and what their traffic patterns are. If you know where the worker ants go to forage, you can interrupt their habit with a trap and bait.
Early in the morning when they are most active, you can then place the bait in the middle of this travel path and force them to take it back to their queen. Once they do this, and the queen feeds from the bait this will slowly kill the entire colony within two weeks and you will have no more ant issue in your yard.
If you cannot locate the travel path or any of the mounds an entire lawn treatment would be an effective way to kill off the colony. This plan will treat the whole lawn so even the underground colonies will get affected once your water in the treatment. This is not the same as baiting them because you are not actually baiting the ants–you are using a pesticide to kill of the entire colony.
Whenever possible use a liquid or a gel bait, these are the most effective ways to guarantee that the ants are attracted to the bait and the high water content of the liquid allows the ants to consume the bait faster and thus killing off the population faster.
All in all, killing off an entire ant colony requires patience and persistence. If one strategy does not work, do not get discouraged. Continue trying different methods until the problem is gone.