In contrast with this Dermacentor nitens is a one-host tick, i.e. only larvae are infective. It occurs in Southern USA, Mexico, Central America, several Caribbean Islands and in tropical and subtropical South America. It affects mainly horses but can also feed on cattle and other livestock. It is typically found in the ears, which can be virtually filled with ticks. They can also congregate in the nostrils, in the mane, around the anus und in the underbelly. Such highly infested animals attract screw-worm flies that ley their eggs on the tick wounds.