ixodid

Ixodidae, commonly called hard ticks, are a large family of ticks within the order Ixodida. They are distinguished from soft ticks (Argasidae) by a hardened dorsal shield called the scutum, visible mouthparts, and longer, more persistent blood meals. Most hard ticks have a three-host life cycle: eggs hatch into six-legged larvae, which attach to a host and feed for several days before dropping off to molt into eight-legged nymphs; nymphs repeat the process and then adults feed and mate, with females finally dropping off to lay large numbers of eggs.

Morphology includes a capitulum (mouthparts) projecting anteriorly and the scutum on the dorsal surface; in many species the scutum is more extensive in males. The first pair of legs bears sensory organs such as Haller's organ, which detects host cues like carbon dioxide, heat, and odors.

Ixodidae are found worldwide, especially in warm temperate and tropical regions, in habitats where hosts are available. Genera include Ixodes, Dermacentor, Rhipicephalus, and Amblyomma. They are medically and veterinary important as vectors for pathogens: Ixodes species transmit Borrelia burgdorferi (Lyme disease) and other agents; Dermacentor and Rhipicephalus can spread Rickettsia spp.; tick-borne encephalitis virus is transmitted by several Ixodes species in Eurasia; Babesia and Anaplasma infections also occur.

Control measures include personal protection, environmental management, and acaricides; prompt removal of attached ticks reduces disease risk.