When a tick feeds it takes up whole blood, extracts the water (about 70-75% volume) and injects the water back into the host. For this reason, they are efficient vectors of a variety of disease causing organisms such as bacteria, spirochetes, rickettsiae, protozoa, viruses, nematodes, and toxins. A single tick bite can transmit multiple pathogens as well as creating secondary infections and allergic reactions. Ticks therefore are the most common transmitters of vector-borne disease in the U.S.
Ticks have four stages in their life cycle, and all require blood from a vertebrate host to survive and complete their development. Like most other arachnids, adult ticks and immatures (nymphs) have four pairs of legs; the larvae (hatchlings) have three pairs. Although there are many species of ticks in Arizona, humans are likely to encounter only three. Two of these, the brown dog tick (Rhipicephalus sanguineus) and the Rocky Mountain wood tick (Dermacentor andersoni) are “hard ticks”, which belong to the family Ixodidae. The third species, the adobe tick (Argas sanchezi) is a “soft tick” belonging to the family Argasidae.
Rodents and deer are most often associated with ticks; however, between the many species of ticks any wildlife in the yard may be infested. The brown dog tick rarely attacks humans, but is the most pestiferous species from the standpoint of the Arizona homeowner because it is a parasite of their canine pets. During their lifecycle, they frequently drop off the host then climb up walls and vegetation and reattach themselves to a passing host. Larvae can survive as long as eight months and adults as long as 18 months without feeding.