Demodex folliculorum (Simon) and D. brevis Akbulatova of Man: Redescription and Reevaluation

Demodex folliculorum and D. brevis are redescribed using statistical methods for meristic data and standard generic morphological criteria for all stages. Such data show that these are distinct species. Histological studies indicate that each of these utilizes different niches: D. folliculorum the hair follicle, D. brevis the sebaceous glands. Both species have life cycles consisting of ova, larvae, protonymphs, nymphs, and adults. Population counts of these stages revealed ratios of approximately 3.5:1.5:1.0:1.6:14.6 for D. folliculorum and 8.5:2.6:1.0:3.2:34.7 for D. brevis. The sex ratios (male: female) were 1:4.5 for the former and 1:3.4 for the latter. It is suggested that all host-parasite data obtained since Simon (1842) should be reworked in view of the fact that these two species are found on tle same host species, Homo sapiens, and even the same host individual.