Question: There is a bag of sugar that is full of **dead** weevils. These tiny insects are just the same size as sugar particles. If they were alive, I could expose them to the sun and they would fly away. If their size were different than the sugar particles size, I could filter them through a mesh. Any practical suggestions to get rid of these dead insects and save the sugar?

Answer: 
You might be able to get rid of the weevils, but what about any waste they've excreted? They've been living, breeding, eating, defecating, and dying inside that bag of sugar. I'm not sure if it's wise to use that sugar, even if you could remove the weevil bodies. You've probably got some unwanted bacteria in there that will taint whatever product you want to use the sugar in. For example, if you use it to sweeten some home made cider, you'll probably end up with cider vinegar after a few weeks.

Sugar is cheap, and easy to replace. Unless you're talking about a very large quantity (on an industrial scale), it's probably wiser to write it off.

How about using preventative measures, to stop this from happening again?

A few years ago, I had a problem with weevil infections in my bakery cupboard. They would get into my flour, sugar and cornflour. I would then throw out my supplies, clean my cupboard, and buy new supplies. A few months later, I would find that my new supplies were also infected! It was becoming an expensive problem.

I decided to wrap all of my baking supply bags in plastic bags. The idea was to isolate any infected bags, and stop it from spreading to any other bags. I've never had any problems since.
how much money are you talking about? Dead Weevils (yuk!) I'd toss the whole bag and buy another rather than swallowing dead weevils. Not my kind of protein.