LOUSE-MITE 



337 



armpits or on the genitals, is at first painless and unnoticed, 

 but the mite remains attached at the wound from one to three 

 days before dropping to the ground to transform to the nymphal 

 stage. The bite of the mite is said to develop into a tiny sore or 

 inflamed spot in the region of which the lymph glands become 

 swollen and painful and flood fever follows. The nymphs and 

 adults of this mite have. recently been found by Nagayo and his 

 fellow-workers in Japan. 



The transmission of kedani by this mite is the only positive 

 instance of human disease carried by Acarina other than ticks. 



Other Occasionally Parasitic Species 



There are many species of mites, of several different families, 

 which under abnormal circumstances or by sheer accident may 

 become troublesome parasites of man. Nearly all mites secrete 

 salivary juices which have 

 a toxic effect when injected 

 into the blood; therefore 

 any mite which will bite 

 man under any circum- 

 stances may become a pest. 

 In nearly all cases the symp- 

 toms of attacks by mites are 

 similar — hivelike or rashlike 

 eruptions of the skin, in- 

 tense itching and in severe 

 attacks fever. 



Louse-Mite. — One of the 

 most important of the occa- 

 sionally parasitic mites is 

 the louse-mite, Pediculoides ventricosus (Fig. 138), belonging 

 to the family Tarsonemidse. This is a. very minute species, 

 barely visible to the naked eye, which is normally parasitic 

 on grain-moth caterpillars and other noxious insects, and there- 

 fore beneficial. These mites live in stubble, stored grain and 

 bea,ns, cotton seeds, straw, etc., attacking the various insects 

 which infest these products and becoming numerous in pro- 

 portion to the abundance of their prey. The female has the 

 remarkable habit of retaining the eggs and young in her abdomen 



Fig. 138. Louse-mite, Pediculoides ventri- 

 cosus ; 5 ■ unimpregnated female ; $ , male, 

 X 150. (9., after Brucker from Webster; 

 $ , after Banks.) 



