Ant lions would not make a significant dent in any ant population. They just take an ant here and an ant there. Kinda like real lions, they just thin the herd a bit. They also require constantly dry, undisturbed soil for their "sand traps" to work. I have some in my yard, but only under the tractor shed where rain never falls and the soil is sandy and loose. Although the last time I looked I couldn't find them, I think I might have accidentally stepped on them previously.