I currently have rice/beans/legumes stored in 5 gallon buckets with alpha seals. Do I need to repackage food in in mylar bags?

I have beans and rice still in the bag that I stuffed into homer buckets over five years ago and it's fine. I also have cracked corn over five years old in a 55 gallon plastic barrel and it's also good. Now other grains like wheat should probably be treated to avoid weevil infestation. One method is vacuum sealing in mylar bags and adding an O2 absorber. If you use this method you DO NOT need food grade buckets! That is a waste of money, since the contents are already protected by the bag. Another incorporates adding diotomaceous earth to the bucket. If you are going to use the sealing method 5 gallon bags are fine for 2-4 people. Remember that white rice has a long shelf life so the rice will keep fine after opening that size bag. I once used a vacuum cleaner and an iron to seal bags. Not pretty but it worked.

If you want it to last beyond 5 years and stay good.

We use the mylar bags w/oxy absorber from amazon. Its stupid easy with a hair straightener. I have had weavels in all grains. You are better off doing it this way while matetials are available. Also you can re seal the mylar several times if you do it right. We are experimenting with DE also, as a back up plan. Just in food grade buckets. Thats what the amish use to store grain around us. Even they have issues with bugs .It takes several years to get a good system for you. Good luck!