I think the evil crawdad is called "Rusticus Immunus" or something very close.

He will take over your pond if transplanted.

My question was really out of curiosity, not the intent to buy crayfish from the south.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."