Evidence from double infestations for the specific status of human head and body lice (Anoplura)

Samples of head and body lice obtained from Ethiopians suffering from double infestations were mounted on microscope slides and measured. The mean length of body lice (f 4.4 mm; m 3.8mm) was greater than that of head lice (f 3.5 mm; m 2.9 mm), but the best discriminate was the length of the tibia of the middle leg (f 425/296 mm; m 421/291 mm). No intermediate specimens were found in these double infestations, although intermediates can be produced experimentally by cross-mating. Since populations of head lice and body lice remain distinct it is concluded that they represent two distinct species, Pediculus capitis De Geer and P. humanus Linneaus.