Ewing — Significance of Parasitism in Acarina. 5 



Depending upon the nature of the food eaten. 



Those living upon the bodily tissues. 

 Those living upon live tissues. 

 Those living upon dead tissues. 



Those feeding upon partially digested food. 



Those living upon blood of the species affected. 



Forms feeding on secretions. ' ; 



Forms feeding on excretory products. i. 



Forms living upon the eggs of the species affected. 



Forms living on spermatozoa. 

 Depending upon adaptation to the parasitic life. 



Facultative parasites. 



Obligatory parasites. 

 Depending upon the stage of degeneration of the locomotor organs. 



With wings. 



Without wings. 



Capable of walking when off the host. 



Incap.^ble of walking when detached from host. 



"Without legs. 



Taking into account the nature and habits of the organ- 

 isms attacked. 



Depending upon whether the organism attacked Is a plant or an 

 animal. 



Photophagous parasites. 

 Zoophagous parasites. 

 Depending upon the free state, or the stage of parasitism of the 

 organism affected. 

 Primary parasites. 

 Secondary parasites. 

 Tertiary parasites. 

 Depending upon the conditions Imposed by the life of the host. 

 HydroxenouB parasites (with an aquatic host). 

 Geoxenous parasites (with a terrestrial host). 

 Aeroxenous parasites (with an aerial Host). 

 Depending upon the number of hosts. 

 Monoxenous parasites. 

 Heteroxenous parasites. 

 Bixenous. 

 Trixenous. 

 Tetraxenous. 

 etc. 



Taking into account the interrelations of the parasites 

 and organisms affected. 



Depending upon the position of the parasites in relation to their 

 hosts. 



