Growing up on a dairy farm, the bugs do not surprise me.
Grain has mold, fungus, feces, urine, bugs, weed seeds, dead animal carcases (rat, mice, racoon, possum, etc...), maggots from rotting carcases, (grease, oil, fuel from farmers machinery), foreign grain seeds, animal vomit, viruses, rotting grain, crickets, grasshoppers (live), bird sh**, etc... you name it, it's probably in there.
It's some of the dirtiest stuff you can imagine... then it's "cleaned" (more like sifted) by the combine and a fanning mill.
There are certain limits of these things that will be tolerated when the farmer sells their grain at the market or mill.
Of course it's suppose to be stored under sanitary conditions. The "grainery" we had was well over 100 years old and had about 2 feet of rotten grain onto which we placed each years new harvest. Of course each years harvest contributed to that rotten layer on the bottom.
When entering the grainery, one could here rats, mice and racoons scattering and see the signs they left sitting on top of the grain.
The working conditions were really poor, (no one should have to breath dust from these things)...
I remember going to load straw at an old timers farm. He spotted a racoon in the straw mow and grabbed a pitch fork, repeatedly driving the pitch fork through the animal until it was dead. Now a racoon is a fierce creature but that didn't stop this old timer. I had never heard an animal screech and snarl so loud. Of course he threw the dead carcass next to the pile of oats in his "grainery" saying he would get rid of it after loading the straw.... This was called "forkin' 'coon" and even Little House on the Praire has a reference to it when Chuck Ingalls, carrying a pitch fork, says to his wife, "I'm going to fork 'coon!"
So yea, good times on the farm.