Ixodidae

Definition

A family of ticks in the order Ixodida, comprising the hard ticks or scale ticks, distinguished from soft ticks (Argasidae) by the presence of a scutum—a hardened dorsal shield covering part or all of the idiosoma in adults. Ixodidae includes approximately 750 species across 14 genera, with subfamilies including Ixodinae, Rhipicephalinae, Amblyomminae, Haemaphysalinae, Hyalomminae, and Bothriocrotoninae. Members are obligate ectoparasites of vertebrates, with life cycles typically involving larval, nymphal, and adult stages that may parasitize one, two, or three host species sequentially. Many species are medically and veterinary significant as vectors of pathogens including Borrelia burgdorferi (Lyme disease), Rickettsia rickettsii (Rocky Mountain spotted fever), and tick-borne encephalitis virus.

Etymology

From Ixodes, the type genus (Greek ixōdēs, 'sticky') + -idae, family suffix.

Example

Ixodes scapularis, the black-legged tick, is an ixodid responsible for transmitting Lyme disease in eastern North America.

Synonyms

• hard ticks
• scale ticks
• ixodids

Related Terms

• Argasidae
• Scutum
• Ixodida
• Acari
• Parasitiformes
• Tick
• Vector
• Ectoparasite
• three-host tick
• Rhipicephalus
• Ixodes
• Dermacentor
• Amblyomma

Usage Notes

The term 'hard tick' refers specifically to the sclerotized scutum present in Ixodidae; this structure is absent in Argasidae (soft ticks). Ixodidae is used as a family name in formal taxonomy and as a general identifier in medical and veterinary contexts. The family is sometimes referred to informally as 'ixodids,' though this plural form properly refers to member species or individuals rather than the taxon itself. When discussing disease transmission, specialists often distinguish between ixodid vectors and argasid vectors due to differences in feeding behavior, pathogen retention, and host associations.