Without a discription of what they look like or even pictures there is really not much we can tell you. There are two types of mites commonly found in a snakes enclosure. One of them being wood mites which is not harmful to your snake. They are commonly found on wood substrate like aspen, coconut husk and cypress. Cedar of course can also carry these. These are very tiny white mites.
The other type of common mite is kind of like lice or flea to snakes (and other reptiles). They are black and can come from almost everywhere. If you walk out side and pick one up on your shoe, well, that is just an example. Reptile mites can also be found in wood chips, especially the bags you pick up at a garden center and is stored outside.
Cedar is deffinitely something you want to get rid of right away. Take it out now and in the mean time use old new paper or paper towel for substrate until you can get something more suitable.
Editted....
After seeing the pictures, I believe these are a gnat (type) of fly larvae. Can definitely be brought in from outside, flies living in your home, or from the substrate. It maybe a smart idea now to remove the substrate. As far as I am aware these are harmless to your snake, but doesn't mean they should live there either.
Reply With Quote