CHAPTER XVI 

 ORDER ANOPLURA* 



The True Lice 



The members of this order are wingless parasitic insects with piercing 

 and sucking mouth-parts. Their development is without metamorphosis. 

 Cerci absent. 



The order Anoplura is composed of the true lice. These are small 

 wingless insects, which live on the skin of mammals and suck their blood. 

 They are sharply distinguished from the Mallophaga or 

 bird-lice by the possession of piercing and sucking 

 mouth-parts. 



The body is more or less flattened (Fig. 142). The 

 head is free and horizontal. The compound eyes are 

 vestigial or are wanting. There are no ocelli. The 

 antennas are three-, four-, or five-jointed. The mouth 

 is furnished with a fleshy, unjointed proboscis, which 

 can be withdrawn into the head or extended to a con- 

 siderable length. Within this proboscis are two knife- 

 like stylets; and at its base, when extended, there is a 

 wreath of recurved hooks. These hooks serve to anchor 

 firmly the proboscis when inserted in the skin of the in- 

 fested animal. 



There is a single tarsal claw, which is opposed by a 

 toothed projection of the tibia, forming an efficient 

 organ for clinging to the hairs of the host. The abdomen consists of nine 

 segments; there are no cerci. 



The eggs of the true lice are commonly known as "nits." They are 

 attached to the hairs of the host by a glue-like substance. The young 

 lice resemble the adults except in size. 



The order Anoplura is a small one of not more than 100 species at the 

 present time. The most familiar forms are those infesting man and the 

 domestic animals, horses, cows, sheep, swine, dogs and cats. 



The three species of lice parasitic on man belong in the family Pedi- 

 culidas. They have comparatively large, convex, pigmented eyes and the 

 proboscis is short. 



The most common species on man is the head -louse, Pediculus capitis. 

 It lives among the hairs of the head and attaches its white eggs, or 

 "nits" to the hairs. It is most common on the heads of children who 

 live under unsanitary conditions. 



The body-louse, Pediculus corporis, (Fig. 143), lives on the body, espe- 

 cially on the chest and back. It increases enormously among soldiers who 

 are unable to bathe frequently. During the world war the "cooties," as the 

 * Anoplura: anoplos (avoirXos), unarmed; oura (ovpa), tail. 



92 



Fig. 142. — Louse of the 

 horse. (From Law.) 



