When I lived in Bahrain for a while, all the rice - packed or not - had weevils in it. Gave me a bit of a shock the first time, I must admit! However, we just used to pour cold water over it, stir it up a bit, then scoop out the weevils as they floated to the surface. And if a few got by the process, well, its only protein, and therefore good for you. Just think of them as land-based prawns....................
Reason for asking - I had some flour in the cupboard that had been opened and the top of the bag just folded down any way went to use it some time later and noticed what i think were weevils they were quite minute I allways imagined weevils to be of maggot to small grub size proportions so is this some thing in the flour allready and manifests with time or some thing air born that gets into the flour - made me thick maybe flour has not got a good shelf life
Best bet for storing flour safely is cold and dry and as clean as possible. The usual infestation seems to be psocids. Tiny wee, just coloured, beasties. All female, and self reproducing, so if only one survives your scrubbing attempts, it's one too many
Small portions, no more than a bag load to a jar/container, and scrub thoroughly inside and out (and where it was stored) every time it's emptied.
It's also a good idea if you are at all dubious about the flour you've just bought, to put the pack into the freezer for 72 hours. That'll kill off any eggs or larvae even if there are no obvious signs of insect infestation.
Not generally harmful, though they (bits/ waste products) can cause allergice reaction in sensitive individuals.
I find brose, pease meal, is a pest to keep I only ever keep it in a sealed jar now, and I generally just keep dried peas and make my own because the commercial stuff just seemed to crawl with in weeks.