some say place the rice bag ( open it ) under strong sun
You did not include, putting nettings across the rice bag, or you will find birds swarming all over. Does anybody notices that rice bought from NTUC Fairprice have plenty of weevils? I used to place my rice bin at the bottom cabinet, next to the LPG cylinder and faced the problem of weevils for a long time, especially rice bought from F-price. I asked around for a solurion, nobody knew any answers. Eventually I figured out it was the indirect heat that is hatching the weevils in the rice, for the rice bin, next to the LPG cyclinder is on top of my desktop burners. I moved the rice to the kitchen top, away from the heat & avoided buying rice from F-price if I can. I have less incident of weevils, none for a very long time. I buy my rice from other supermarkets or from the provision shop near where I live, by the kilos, what they call "new rice" in Hokkien. I do have occasional weevils, if I don't use the rice for a very long time, but compared with those I bought from F-price, which you find, plenty weevils crawling out of them very quickly.
I guess, it is heat that germinate the eggs that are already present in the rice that produces the weevils.