Why are Hedgehogs illegal in some places?

Usually when states ban certain animals or fish as pets, it's because their afraid if the animal is either let loose by a "bad" owner, or if it escapes, it can wreak havoc on a lot of the natural species in the area. Not sure if they still are, but ferrets were even illegal in California. Piranhas are illegal in a lot of the Southern states, because they'll survive the winters down there and would kill off alot of the natural fish species. Florida is a great example of plants, trees, animals, etc. that have non native invasive species killing off native species. It's not directly related to your question, but look at fire ants or killer bees. They're pushing their way North ward, and either breeding with the native species or killing them off. Some of it I think it's absolutely ridiculous, especially if you can go across the border to another state and buy a gerbil to bring home, but I guess I do understand their reasoning...sometimes lol.