A good example is warning coloration in aposematic species. Such displays are often combined with warning coloration. Other species such as the rainbow grasshopper have warning coloration which deters predators. Most spiders are insufficiently dangerous or unpleasant-tasting for warning coloration to offer much benefit. Their variety in warning coloration is used for their visibility, toxicity and resistance to predators. The existence of unequivocal warning coloration is therefore clear evidence of natural selection at work. Aposematism, or warning coloration, is another factor that influences antipredator behavior. The nature and function of warning coloration, as illustrated by the mammalia. Aposematism is the warning coloration to signal potential predators to stay away. Ladybirds are aposematic (with conspicuous warning coloration), so camouflage cannot explain the distribution. A defensive use would explain the Gila monster's bright warning coloration. In 1867, in a letter to Darwin, Wallace described warning coloration. Warning coloration evolves in response to background, light conditions, and predator vision. Blue-ringed octopuses ("Hapalochlaena") from Australia and New Guinea have a powerful venom and warning coloration. More recently, the genetic basis of monarch migration and warning coloration has been described.