Yes, those are bugs that infest dry carb-rich products like rice, flour, crackers and starches. They leave very thin cobwebs in places that they infest.
They’re my worst nightmare, because I have coeliac disease and I have about €400 worth of medical food in my pantry 😯
These bugs can eat through plastic bags and may have gotten into it while being stored in a warehouse. Sadly they’re pretty common and difficult to get completely rid of. That counts for both the home and the food production/ packaging/storage industry.
As mentioned: I would indeed return these pellets. And then I’d do a thorough inspection of your kitchen, pantry and any other place where you keep dry foodstuffs. Sieve flours to check for bugs, check for cobwebs with a flashlight, and repackage things. Use plastic tubs, metal tins or glassware to store your things in, so the bugs can’t reproduce in there.
Hope this helps and that it’s not too bad yet!