Oxygen absorbers can lengthen the shelf-life of foods by reducing the oxygen levels in a sealed container of dry food. Their role in the removal or binding of oxygen is what would kill any insects or larvae present.  

All oxygen absorbers are made of iron powder that reacts quickly with moisture and oxygen in the air.  For these to be useful for any length of time, the container must be completely sealed.  The canning jars you mention with a lid with a gasket and the ring tightly closed should work. 

When purchasing, look for mention of FDA approved, food safe products from a well known manufacturer or distributor.  Make sure they are packaged airtight so they won’t have already reacted with the moisture and oxygen in the air when you get them.  Oxygen absorbers come in a variety of sizes and should have some indication in the packaging of how much of the food per packet should be sealed together. 

https://issuu.com/usuextension/docs/food_storage_booklet2_49bc3ab844f0dc

Pages 91 and 92 of this publication have more details and also give suggested guidelines for quantity to use.