considering that eucalyptus oil can be poisonous if ingested and they likely groom them selves i would think it would be a minor stomach upset that they get every time they are near them. as far as the mint just try to not put it in the room that the snake is in if you start in one room of the house furthest from your snake and then work your way out including the base boards or pad of your house on the out side you should get rid of them and only put the minor amounts int he room with the snake. but i don't know if mint is something they are affected by.