Meal worm eggs are even smaller than sand grains, but you can see them with the naked eye if the adults lay the eggs on a flat surface such as a piece of newspaper or inside a discarded toilet paper roll. The eggs are about the same size as the period at the end of this sentence.
Allow me to give you a tip about that drawer file box. They are not secure. Eventually, the larvae will reach full size and will clump in corners of the drawer. They pile up, allowing the ones on top the pile to reach the top edge of the drawer sides.
If you contemplate meal worms at large in your house, or wherever you have the container, as a desirable outcome, by all means use the file box. This happened to me. The meal worms climbed out of the drawers and colonized the inside of the file box before entering the bigger world of my kitchen. It was great fun rounding them all up.
A better choice would be Sterilite shallow storage trays with lids. Adults also find ways to escape unless confined to containers with straight smooth sides and lids. They can learn to fly if they find themselves free for any extended period. This, too, I have experienced. Good times.