Ticks are notorious as vectors of human and other animal disease agents. They transmit a greater variety of infectious organisms than any other group of bloodsucking arthropods and, worldwide, are second only to mosquitoes in terms of their public health and veterinary importance. Ticks constitute the suborder “ Ixodida ” of the order “ Parasitiformes ” and are exclusively parasitic. The Ixodida contains three families: the Ixodidae , Argasidae , and Nuttalliellidae . The major external regions of ticks are the capitulum (gnathosoma), idiosoma , and the legs. The internal organs are bathed in a circulating fluid, the hemolymph. Their life cycle includes four stages: the egg, larva, nymph, and adult. Ticks transmit numerous protozoan, viral, bacterial (including rickettsial), and fungal pathogens. They are also injurious to domestic livestock and wildlife because of the blood loss that occurs when large numbers of ticks feed. The wounds that they produce create sites for secondary infections and diminish the value of livestock by damaging their hides.