just eat em
soap
boiling water (as in: 90-100 degrees celsius water)
poison
radiation
liquid nitrogen
molten aluminum
what you can also do is track down the ant queen and murk it
Flip the backyard upside down, they won’t know what hit em
heat up boiling water / oil and throw it on them, acid rain i guess
thermonuclear bomb
you will never have to worry about that problem, or any other problem, ever again
It’s a cure-all
side affects may include extinction of a city, buts it alright
Acceptable.
Get an X-ray machine or electron gun or smth and ionize your backyard
Keeps ants out for the next few million years