If the bugs are white there is a chance they could just be wood mites which are harmless to your snake. We recently just had the same problem with our snake and decided to clean his cage and treat him for mites just as a precautionary. He is also currenlty on paper towel to see if any mites show up (black on a white background). If you do a search on mites on this website there is a home remedy for mites that is pretty inexpensive to make. You can also try what Mike said and freeze the substrate first. Hope this helps.