Pediculus humanus (Linnaeus, 1758) & Linnaeus, 1758

Until valid evidence to the contrary is provided, two subspecies are recognized for this louse. The nominate subspecies, Pediculus humanus humanus is the body louse, while Pediculus humanus capitis is the head louse of humans. [ex. Durden, L. A., Musser, G. G. 1994. Bulletin of the American Museum of Natural History 218: 1-90]. Two distinct subspecies have been recognized; Pediculus humanus humanus Linnaeus for the body louse and Pediculus humanus capitis de Geer for the head louse (Hemming 1958). Ferris (1935, 1951), Buxton (1946), and many other workers have indicated that it is often impossible to make a positive determination of a single specimen as either a body or a head louse, although populations of these two subspecies can be determined. De Geer (1778) first used trinomials, Pediculus humanus capitis for the head louse, and Pediculus humanus corporis for the body louse, and Latreille (1803) was the first to restrict the name Pediculus humanus as a distinct species for “le pou du corps” and Pediculus cervicalis for “le pou de tete.” Although Busvine (1978) and Schaefer (1978) recently advocated the specific status of human head lice and body lice, the taxonomic status of Pediculus humanus populations on human head and clothing and other anthropoid hosts remains unresolved and requires an indepth study because of their considerable overlapping variations and hybridization. The following summary (based on Buxton 1946, Ferris 1951) lists some of the differences between the two taxa. SIZE AND COLOR: (P. h. humanus) Larger and lighter, Female, 2.4 to 3.6 mm Male, 2.3 to 3.0 mm; (P. h. capitis) Smaller and darker, Female, 2.4 to 3.3 mm, Male, 2.1 to 2.6 mm. ANTENNA: (P. h. humanus) Longer and more slender, third segment usually longer than wide; (P. h. capitis) Shorter and stouter, third segment often as long as wide. ABDOMEN: (P. h. humanus) Indentations between abdominal segments less prominent; (P. h. capitis) Indentations between abdominal segments more prominent. PARATERGITES: (P. h. humanus) Do not extend apex of their abdominal lobes into intersegmental membrane; (P. h. capitis) Do extend apex of their abdominal lobes into intersegmental membrane. POSITION ON HOST BODY: (P. h. humanus) Below the neck, often on garments next to skin when not feeding; (P. h. capitis) On neck and head, particularly behind ears and on back of neck. EGGS: (P. h. humanus) Glued to body hairs or on clothing worn next to body, particularly along seams; (P. h. capitis) Glued to head or neck hairs. [ex. Kim, K. C., Pratt, H. D., Stojanovich, C. J. 1986. The Sucking Lice of North America, p. 241: Pennsylvania State University]