GENERAL CONSIDERATION OE DISICASI- 



^HVt!^™ KtArWrt**^ 



Fj^ 44. — ^^eloI>llily:us Ovinus, 



Dorsal view of adult. d. 



"\"untral \-iL\\- of adult e. 



Mouth parts enlarged. f. 



after Niles. 

 Terminal si.i^nie 

 Shell of pupa. 

 Pupa. 



horse louse (Trichodectes Pilosiis) and feathers, e. s;'., the 

 chicken louse (Menopon Pallidum) others abstract blood, e. g., 

 the hog louse (Hematopinus Suis), Itch mite (Sarcoptes scabei 

 variety canis), and still others may consume tissue cells other 

 than blood cells as epithelium. Reproduction of arthrojioda is 

 about the same as it is in helminthes. 



Disease resulting from infestation of arthropoda is due 

 primarily to irritation induced mechanically or by chemic pro- 

 ducts of the parasites, secondarily to loss of blood. 



