i asked NDN a smiliar thing last night. How come you can flick a fly or tiny winged thing, or evne an ant, and flick it hard, and they still just wander off.

And i believe your ant thing is to do with weight/velocity.

It wont travel fast enough due to weight to pick up the speed to cause it ti tumble allowing for a nonsafe landing at higher speed due to the shape of its body. If it falls slowly, it can slow itself down.