Since the chickens would really appreciate the protein the weevils would have provided why on earth throw it out? It takes several weeks for the weevil eggs the hatch and by then the chicken feed should be used up anyway so adding Diamotaceous Earth to chicken feed should be a waste of money.
The second question that comes to mind is which DE, food grade, or pool grade, did you buy?

OK, good questions!
"Threw out" means I threw it on the ground. The chickens only get let out to free range after work, so they didn't have a chance to scarf it up at the moment I threw it on the ground. The weevils were tiny little things, anyway; probably not even 1/4" long. The girls are so spoiled (I've been known to catch grasshoppers for them!) they won't even eat earthworms, so 1/4" long weevils probably wouldn't have interested them much.
It was food grade DE purchased at a feed store which specializes in organic products.
Don't know about the hatch time for these weevils, but I put the feed and the DE in the container on a Saturday and two Friday's later I noticed the problem when I got to the bottom of the container. I'm adding the DE because a couple of my hens have poo which looks like that expanding yellow foam, and several folks at BackyardChickens.com said that was an indication they had worms. They recommended sprinkling DE over their food as an anthelmetic. I never expected to have bugs in the food after that, though!
Do you think DE is just a myth, like grits for fire ants?

As long as the DE is dry it is effecticve, but DE is a passive control. The target must make contact with it, and there must be enough in the feed mix to be effective. The weeils in your feed are not the source of internal parasites, if your birds have them.

Here is a link that might be useful: Poultrry parasites

So if DE has to be dry to be effective, how could it possibly act as a wormer?

I know the weevils and the roaches aren't the parasite source; the fact that those critters were LIVING in DE is what made me question whether DE is really effective at all, or if it's just an urban myth.

Thanks for your input.

DE is effective against CERTAIN insects, but it has to stay dry and it is not effective against all pests.

The usefulness of DE is not an urban myth. And it also doesn't need to stay dry in order to be effective. It works BETTER on most critters that way, but will still cause problems for them when wet. It is quite effective against certain internal parasites, both inside an animal and after it has been excreted (in poop).