158 



(aquatic or terrestrial) ; some are parasites of plants^, 

 certain Mites (of the Family Gamasidae) are blood-suckers,, 

 and the Family Ixodidae or Ticks are blood-sucking para- 

 sites of reptiles, birds, and mammals including Man. Many 

 of the blood-sucking species convey pathogenic organisms 

 (e.g., Spirochaetes a ad Piroplasmata) to Man and domesti- 

 cated animals. The Order includes numerous forms im- 

 portant in relation to disease. 



Name some Mites which are Important in relation to Man 

 and Domesticated Animals. 



fEriophyes (syn. Phytopus) ribis. The Currant Gall-mite. A 

 .degenerate worm -like form with very short legs (two pairs- 

 only) and the posterior portion of the body tail-like and 

 ringed. Causes " big-bud " disease of fruit bushes. 

 fDemodex folliculorum. Degenerate and worm-like. A common 

 parasite in the hair foliicles and sebaceous glands of Man., 

 ^D. caninus causes " follicular mange " in dogs. 

 fSarcoptes scabiei. Itch-mite of Man and animals. Forms galleries- 



in the skin and causes " scabies.'' 



[Sarcoptes mutans. Produces " SCaEy-leg '' in poultry. 

 fPsoroptes. Produces " sheep-scab." 

 *Dermanyssus gallinae. The Red-mite of poultry. Occasionally 



attacks Man, causing skin irritation. 



"(Pediculoides ventricosis. The Grain-itch Mite. Attacks dock- 

 labourers unloading grain, etc. Causes dermatitis. 

 *Trombidium holocericeum. The Harvest-mite. Its larva,. 

 *Leptus or Microlrombidium autumnalis, is the so-called 

 " harvest-bug " which attacks Man. 



*Microtrombidium akamushi. The Japanese Harvest-bug. Trans- 

 mits the very fatal disease, kedani, or river fever of Japan. 

 *Blood-sucking. 

 | Parasites. 



Family Ixodidae (Ticks). 



Write a short Description of the External Features of the 

 Ixodidae or Ticks. 



The body is roughly oval in shape and flattened dorso- 

 ventrally. The abdomen is fused with the prosoma. The 

 integument is leathery ; and there is generally a dorsal 

 shield or scutum. This shield, in the male, covers the 



