I called and asked the manufacturer of one of the "blend" mulches last year. It is:
10% cypress
50% pine
40% "whatever we were cutting that week"
I would stick to 100% cypress from a reputable source.
Alright, darn, I couldn't find 100% cypress anywhere around here, my lowe's doesn't carry the kind that other people got for their snakes unfortunately, I guess newspaper it is until I can find a reputable source for it or get a email back from the company.