What wood is safe for a corn snake to have in its tank?

I would use a store bought artificial log. Try not to use a real log, or one that you find.. Artificial logs are the best as they are clean. If you use a log that you find, your snake can get parasites and other bad stuff. Corn snakes generally do not need a log. It would be pretty rare to see him/her actually using it, but, a log looks good and if they do end up using it, it'll provide them a way to get exercise.

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If you want bedding for your corn use aspen, do not use anything with cedar or pine in it, (including hides) this affects their respiratory and can cause death.

Aspen is not always the best type of bedding to use.. It clumps together and doesn't hold humidity as well as other substrates.. Shredded coconut can be a bit pricey if you have a collection of snakes, but it is pretty good. Newspaper, although plain, is very sanitary and easy to clean.. (lots of substrates require vacuuming your floor after..)