Although I don't have any personal experience with eucalyptus mulch, my grandparents have eucalyptus trees in there yard - the bark and the leaves are quite toxic (as in they contain a lot of oils) - possibly not enough to harm the snake but it might be quite irritating; of course I guess it's possible that they treat the mulch so that it is no different than cypress don't know. If you do switch use caution and keep an eye out for side effects. I'd personally stick with the cypress - but to each his own! Sorry I guess I didn't tell you much.
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Tosha 
"Stupid is forever, ignorance can be fixed." Don Wood
"Of course, that's only my opinion...and I believe I am God." =) Chris Bianco
7.33.0 Ball Python (Harry and Fluffy and gang)
1.0.0 Angolan Python (Skywalker)
0.0.1 Green Tree Python
0.2.0 Feline (Pippen and Pandora)
0.0.1 Dessert Tortoise (Pope John Paul)
2.2.1 Fish (1,2,3,4)
0.0.0 Pool skimmer rescues for this season