Ixodidae

Ixodidae, commonly known as hard ticks, constitute one of the two main families of ticks, the other being Argasidae (soft ticks). They are parasitic arachnids that feed on the blood of vertebrates and are important vectors of various pathogens. A defining feature is the scutum, a hard dorsal plate; the mouthparts are visible from above, and females expand markedly after feeding.

The life cycle includes four stages: egg, larva (six legs), nymph, and adult. Most species are three-host ticks, feeding once at each stage on a different vertebrate host. After a blood meal, each stage detaches, molts, and seeks a new host. Feeding is typically prolonged, lasting days to weeks, which facilitates the transmission of certain pathogens.

Geographic distribution is global, with greatest diversity and abundance in temperate and tropical regions. They thrive in humid environments with ample vegetation, where they quest for hosts by waiting on vegetation and ground cover. Host associations vary by species, with birds, small to large mammals, and occasionally reptiles serving as hosts at different life stages.

Pathogens transmitted by Ixodidae include bacteria such as Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum, and various Babesia species, as well as tick-borne encephalitis viruses. Transmission depends on tick species, geographic region, and the duration of attachment, among other factors.

Taxonomy and notable genera include Ixodes, Dermacentor, Amblyomma, Rhipicephalus, and Hyalomma; Boophilus has been treated as a subgenus of Rhipicephalus in many classifications. Prevention focuses on habitat management, protective clothing, tick checks, prompt removal of attached ticks, and, for pets, appropriate acaricides.