ixodids

Ixodids, or hard ticks, comprise the family Ixodidae within the order Ixodida. They are distinguished from soft ticks (Argasidae) by a hardened dorsal shield (scutum), a visible capitulum from above, and relatively long feeding periods that can last days. Like all ticks, they are obligate hematophagous ectoparasites and go through four life stages: egg, larva, nymph, and adult.

A typical ixodid life cycle is three-host. After each feeding stage, the tick detaches, molts to the next stage, and seeks a new host. Larvae and nymphs generally feed on small vertebrates or birds, while adults feed on larger mammals, including humans and livestock. Development and seasonal activity are influenced by climate, vegetation, and host availability. Ixodids inhabit temperate and tropical regions worldwide, favoring environments where hosts and microclimates allow prolonged attachment.

Ixodids are important disease vectors. They transmit bacteria, protozoa, and viruses that cause illnesses in humans and animals. Notable examples include Borrelia burgdorferi, which causes Lyme disease (often via Ixodes species); Anaplasma phagocytophilum (anaplasmosis); Babesia species (babesiosis); and Rickettsia rickettsii (Rocky Mountain spotted fever). Different genera contribute to the transmission of various pathogens, with Ixodes and Dermacentor among the best known.

Control focuses on reducing tick contact and habitat, using protective clothing and repellents, landscape management, acaricides on hosts, and, in some cases, vaccination or veterinary interventions. Surveillance and public education are key components of managing ixodid-associated disease risk.