Oat usually hard to get kutu inside. Unless not sealed tightly. Last time my aunt bought a punctured bag of oats. In that same week open the bag and it had lots of kutu inside. Meanwhile the tub of oats that i makan everyday are not infected because sealed tightly.

Rice also same. I tried putting a few whole garlic inside rice. Still those things breed. But the rice smell nice la. Wanna try dried chili or Ginger next.