Aposematic coloration. Conspicuous marking or coloring that is meant to send a signal to a potential predator that its possible prey may be at least distasteful or at most poisonous.

So many examples. A color technique used by butterflies, skunks, snakes, frogs, bees, wasps, and so many others. This butterfly, above is a perfect example of aposematic coloration. Of course, this is a Monarch Butterfly, which eats Milkweeds which contain toxins that the Monarchs store up and pass along to their predators, which make the Monarchs extremely distasteful. And that, with the bright orange and black coloring makes it a perfect example of Aposematic Coloration.