^8 Guide to Insects and Ticks 



o 



from infected to healthy persons, and Clinocoris rohmdahis is 

 known to be the carrier of a piroplasma parasite, Lcishmania 

 doiiovani Laveran and Mesnil, the cause of the tropical disease 

 kala-azar, common in India. 



LICE AND DISEASE. 



Apart from tlie irritation which they cause, in some cases so 

 great as to lead to loss of sleep and nervous prostration, lice are 

 noxious insects because of their capacity for spreading typhus fever 

 and some forms of relapsing fever (those of Europe and North 

 x\frica) ; lice have also been suspected as the infective agent in 

 certain cases of leprosy, tuberculosis and plague. The organism 

 of typhus fever has so far not been identified. That the causal 

 organism undergoes some part of its development in the louse is 

 evident from the fact that lice are especially infective from the 

 fifth to the seventh day after feeding upon a person suffering from 

 typhus fever. The organisms of the relapsing fevers are spiro- 

 chaetes, blood parasites of spirally twisted, thread-like form. 



Lice feed entirely upon blood, which they suck through 

 punctures made in the skin ; they soon die when removed from 

 the body, and differ in this respect from fleas and bugs. Three 

 species of louse occur on man — the clothes-louse or body-louse, 

 Pccliculus JiUHuoiusLiinu. (fig. 12), the head-louse, Pt;(//c»/?/s capitis 

 de Geer, and the crab-louse, Phihirus pubis Linn. These are 

 also found occasionally upon cats, dogs and monkeys living in 

 association with man. Various kinds of mammals, from elephants 

 to shrew-mice, have their own particular species of lice. 



In one of the two sloping-faced cases in the middle of the Hall 

 are shown some specimens and enlarged coloured drawings ( x 50) 

 of the clothes-louse and head-louse. In the same case a series of 

 five lenses is arranged over mounted specimens of a head-louse, 

 some pieces of human hair with nits or eggs of the louse, a 

 clothes-louse, a crab-louse, and a louse (Pediculus schaffi Fahr.) 

 from a chimpanzee. Under the microscope near the bust of 

 Sir William Flower, on the West side of the Hall, is shown a 

 mounted specimen (slide K) of the clothes-louse. 



