What can I use to get rid of ants in my yard?

Yous ant spray or wasp spray

The actual ant should be identified so that whatever you do, will work with that type of ant. There are online identifiers, there are some yard ants that almost no baits/poisons will work on. They don't invade the home and don't sting/bite/whatever. They are just a pain in the ***. Considering they don't really threaten, much like the common cold, not a lot of research is put into trying to defeat them.

If they are fire ants (big mound no apparent entry, when you swipe your food across the top dozens of small red ants swarm out) then Amdro makes a great product that is a bait you sprinkle around the mound (couple Tbls) and the mound is dead in 2 - 3 days. Kills all the way to the queen and she can be 6 ft down in the soil.

You can use ant killer from a puffer pack. You can also place saucers of liquid ant killer near the nests if you have no pets. The latter gets taken into the nest and wipes them out.