Sucking lice

Definition

A parvorder of obligate blood-feeding ectoparasitic insects (parvorder Anoplura, order Psocodea) comprising approximately 550 species that parasitize mammals exclusively. Distinguished by piercing-sucking mouthparts adapted for feeding on host blood and by their dorsoventrally flattened, wingless bodies. All species complete their entire life cycle on a single host individual or host species, with eggs (nits) cemented to hair or fur. Sucking lice are significant vectors of rickettsial and bacterial pathogens, including the agents of epidemic typhus (Rickettsia prowazekii), trench fever (Bartonella quintana), and louse-borne relapsing fever (Borrelia recurrentis) transmitted by the human body louse Pediculus humanus humanus.

Etymology

From 'sucking' (referring to blood-feeding mouthpart function) + 'lice' (plural of louse, Old English lūs, of Germanic origin).

Example

The human head louse Pediculus humanus capitis and the crab louse Pthirus pubis are both sucking lice adapted to specific hair densities and microhabitats on the human body, whereas chewing lice (Mallophaga) feed on feathers, hair, or skin debris and parasitize birds and mammals.

Synonyms

• Anoplura

Related Terms

• Chewing lice
• ectoparasite
• Phthiraptera
• pediculosis
• vector
• Mallophaga
• Psocodea

Usage Notes

The term contrasts sharply with chewing lice (parvorder Mallophaga), which possess mandibulate mouthparts for feeding on keratinous materials. 'Sucking lice' is the functional common name; Anoplura is the formal taxonomic name for the group. Formerly treated as order Anoplura, the group is now classified within order Psocodea (or Psocoptera) based on molecular phylogenetics. The distinction between sucking and chewing lice is fundamental in medical entomology and veterinary parasitology because only sucking lice are implicated as disease vectors.