ENTOMOLOGY

CHAPTER XXLouse Borne Diseases 1w. Dwight Pier~eThe parasitic lice belong to two closely related orders, the Anopluraor Siphunculata, commonly called sucking lice or vermin, and the Mallophaga,called biting lice, differing principally by the formation of themouth parts. The sucking lice are parasitic principally on mammals,and the biting lice on birds, but some of the latter also attack mammals.They at:e more or less definitely limited according to their species todefinite species or genera of animal hosts. All cause great annoyance andworry and probably by their .attack frequently cause death of the host,especially young hosts.We are especially concerned with the sucking lice in this lecture,but will include a few notes on the biting lice. Some of the most seriousdiseases of man, especially when congested in crowded populations or inarmies, are caused or carried by lice. Probably many fatalities amongwild animals and birds are due to inoculable diseases carried by lice, whichhave never been investigated.I. DIRECT EFFECT OF LOUSE ATTACKThe attack of lice on the body is in itself exceedingly annoying andleads to a great deal of itching and scratching. The attack by thevarious species of lice is differentiated by terms applicable to each. Theattack by the body louse, Pediculus corporis DeGeer, or as it is knownby Nuttall (1917), Pediculus humOlTlus var. corporis, is known as PEDIC­ULOSIS CORPORIS. The attack by the head louse, Pediculus humanusLinnaeus, commonly known as capitis DeGeer is called PEDICULOSISCAPITIS. Attack by the pubic louse, Phthirus pubis Linnaeus, is knownas PHTHIRIASIS.1. Types of Pediculosis CorporisNuttall (1917) has described a considerable number of recorded typesof dermatitis caused by louse attack.1 A lecture on this subject was delivered June S, 1918, and distributed in mimeographedform, but on account of the great change in the subject since then, the presentlecture is practically rewritten.286