There's a phrase in the south: "If It's Indigo, Let It Go."I dont mind snakes as long as they are grass snakes or eat vermin, we have some pretty large black snakes here that have a yellow ring around their necks, the locals call them Indigo's they look like they can take on some of the larger field rats.
They're known for hunting poisonous snakes like rattlers and copperheads.
Edited to add: Indigos are black. If they have a yellow ring around their necks, they are a different breed.