They look like the Indian meal moth larvae. They are a devil to get rid of as they will infect everything. They won't actually harm your hamster but don't let them get established in your house or supplies. They make a webbing stuff which rots the food and it's not nice.
Freezing the food in sealed bags will kill the eggs. All your cages need cleaned and the stuff binned far away from the hamsters. Buy only small bags at a time as you need them and have your spare in the freezer. Watch they don't get to your pantry as they like human food too hence the name pantry moths.
https://en.wikipedia.org/wiki/Indian_mealmoth