Agreed w vacuuming. I have 100 (3) children, and larder beetles are my frequent enemy due to the....crumbs my children produce. Vacuuming constantly, and cleaning the pantry and cereal cupboards regularly - using jars/sealable containers rather than the store packages/boxes for things. Everytime I think I have them beat, I find a half eaten granola bar or pizza crust under a bed that proves me wrong. Thats all I got. Its not perfect, but I THINK IT MIGHT BE if snacks didnt appear under beds and couch cushions
one of my kids is celiac, and I tried using a clip on a bag of EXPENSIVE gluten free flour - I had a complete meltdown when I scooped a cup of flour from the bag and found a dried up larder beetle. Had to throw the whole bag out!