Pediculidae

Definition

A family of sucking lice (order Psocodea, suborder Anoplura) containing the single extant genus *Pediculus*, whose species are obligate ectoparasites of primates. Members are dorsoventrally flattened, wingless, and possess piercing-sucking mouthparts adapted for feeding on blood. The family includes the human body louse (*Pediculus humanus humanus*) and head louse (*Pediculus humanus capitis*), historically significant vectors of epidemic typhus, trench fever, and relapsing fever.

Etymology

From Latin *pediculus* (little louse) + family suffix *-idae*.

Example

Pediculidae are distinguished from the related family Pthiridae (pubic lice) by their elongated body form and claw structure adapted for grasping hair shafts rather than coarser pubic hair.

Related Terms

• Anoplura
• Psocodea
• Pediculus
• Phthiraptera
• Ectoparasite
• sucking louse
• Pediculosis
• vector-borne disease

Usage Notes

Historically treated as a separate order Anoplura, Pediculidae is now placed in Psocodea following molecular phylogenetics. The family is sometimes referenced informally as "true lice" in medical contexts to distinguish sucking lice from chewing lice (Mallophaga). Speciation within *Pediculus* remains debated, with some authorities treating human body and head lice as distinct species or subspecies.