Slovenia

In Slovenia, antlions choose their sand as carefully as a chef chooses ingredients. 

The antlion larva digs a funnel-shaped trap in loose sand and hides at the bottom. When an ant steps over the edge, the sand slides towards the centre and the ant goes with it. If it tries to climb out, the larva throws sand at it and sets even more sand in motion.

Slovenian researchers have shown that grain size decides how well the trap works, and that antlions pick the sand that suits them best.