Oh dear, I didn't know this was a problem!
I have never seen any insects, or bits, alive or dead, in or around our hamster's cage and food (excluding some dried mealworms we bought). The only insects I find are usually in my room or the kitchen and definitely came from outside (e.g. wasps
)
Should I start freezing my hamster's food and wooden accessories? We don't have much freezer space...