388 



LICE 



**"" General Structure. 



Lice are small wingless 

 insects constituting the 

 order Anoplura. They 

 were formerly classified 

 as a suborder of the 

 Hemiptera or true bugs, 

 but recent studies have 

 shown the erroneousness 

 of this grouping. The 

 mouthparts are adapted 

 for piercing and sucking. 

 The piercing apparatus 

 (Fig. 171B) consists of 



FIG 171 Mouthparts of a body louse; A, f our nee dle-like Organs, 

 longitudinal section through head ; B, mouthparts 1-1- u j i 



from sac under pharynx and oesophagus; buc. t., One OI which IS the dell- 



buccal tube; m., mouth cavity; ph., pharynx; ces., cate sa li vary duct, which 



oesophagus; retr. sac., retractile sack for mouth- 

 parts; prot. m., protractor muscles of pharynx; 



. 

 Can be Withdrawn into 



-cnt. 



ret. m., retractor; dil m., dilators; d. p dorsal & Uttle Quch under th 



piercer; sal. d., salivary duct; v. p., ventral piercer; 



v. pi., ventral plate = labium (?). (Adapted from pharynx (Fig. 171 A). 



Harrison ' ) This type of mouthparts 



readily distinguishes the 

 true lice from the bird 

 lice, which constitute 

 the order Mallophaga 

 (Fig. 172). In the latter 

 there are nipper - like 

 mandibles fitted for bit- 

 ing instead of sucking, 

 and these parasites feed 

 only on hair, feathers, 

 etc., and not at all on 

 blood. In other respects 

 the sucking lice and bird 



lice show a Considerable 



resemblance t O each 

 ,, 



other, and are now gen- 

 erally believed to be 



closely related. The feet of the true lice are armed each with a 

 very large curved claw, quite grotesque in appearance in some 



FIG. 172. Head of bird louse (from golden 

 eagle) ; ant., antenna. Note breadth of head as 

 compared with thorax, a feature which readily 



distinguishes bird lice from sucking lice. 



