I put it in the freezer for a week - it can take a week to kill moth eggs (which is why I do it after having an outbreak of moths for months!) It's normal for moth eggs to get into all kinds of things - hard to see with the human eye - often pet foods and sometimes flour. And they don't do any harm - except if it gets warm they can hatch! And breed very quickly. Freezing for a week kills the moth eggs.
After a week I take the bag out, wait till it's defrosted and then store it in a lock and lock airtight box (belt and braces! In case any eggs survived). Sometimes though I will get two bags and leave one in the freezer for some time and only take it out when the storage box needs refilling. Up to you really
