I would think that live moss might give the same effect. You could try bed of beast, the finely ground cocohusk stuff. But I did have a baby tomato frog die of impaction from that.
I think your best best is to redesign your caging. A taller cage will have them eating above ground if the insects given are introduced higher up. Remember that these frogs in nature will rarely see if ever the ground. I would even suggest going substrateless.