CHAPTER XIX 

 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. 



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 most 

 familiar examples of the Anoplura are three species that infest man 

 and several species that are found on domestic animals. 



The name Siphunculata was proposed for this order by Meinert 

 in 1 89 1 and is now used by some authors; but the name Anoplura is 

 much the older name, having been proposed by Leach in 181 5, and 

 is more generally used. 



The body is more or less flattened (Fig. 394). The head is free 

 and horizontal. The compound eyes are vestigial or are wanting. 

 There are no ocehi. The antennae are three-, four-, or five-jointed. 

 The mouth is furnished with a fleshy, un jointed proboscis, which can 

 be withdrawn into the head or extended to a considerable length.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 

 infested animal. Authors do not agree as to the homologies of the 

 different mouth-parts of these insects. 



The thoracic segments are fused. The legs are similar; the tarsi 

 consist of a single segment, which is often greatly reduced. 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." The^^ 

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

 yoimg lice resemble the adults except in size. As with the Mallophaga, 

 the ametabolous condition of these insects is believed to be an ac- 

 quired one, a result of their parasitic life. 



This is a small order. Dalla Torre ('08) in his monograph of the 

 Anoplura of the world lists only sixty-five species. These represent 

 fifteen genera, which are grouped in four families. The two following 

 families include all of the species that infest man and the common 

 domestic animals. 



*Anoplura: anoplos (AwTrXoi), unarmed; oura (oipd), tail. 



(347) 



