I have two 50 lb bags of 32% catfish feed that have flour beetles in them. Putting a little diatomaceous earth on top of each one would take care of the problem. From what I have read, it would not be harmful to fish. I read that farmers use it in cattle feed to keep out insects.
Any experience here with that sort of thing?

Sounds like old feed. I would return it to the store.

They gave me another bag that appeared to be totally intact. Let me keep the first bag. The second bag had a few beetles in it, so he gave me a 4 lb bag of diatomaceous earth. It seems to be killing the beetles. No more shipments of catfish food this season to our local co-op. End of season.

We use it to treat empty grain bins before filling them with grain. One brand name is called Insecto , but it is diatomaceous earth. Dead diatoms basically.

It scratches the insects coating causing them to dehydrate and die. Supposed to be harmless to humans or animals.

Diatoms

Wow, that's ingenious.