58 SCAB OF HOG. 
NORWEGIAN ITCH-MITE OF MAN. 
(Sarcoptes crustose Fuerst.). 
This itch-mite is very similar to the common one infest- 
ing man, but is smaller and darker. It was first described in 
Christiana, Norway, and seems to beconfined to that country, 
though it has several times been found elsewhere. It has so 
far as known not been found in Minnesota, and it is to be 
hoped never will find its way into our state, as it is a very 
much worse parasite than the common itch-mite. 
SCAB OF HOG OR THE SCALE-BEARING 
ITCH-MITE. 
(Sarcoptes scabiet var. suis) or (Sarcoptes squamiferus Fuerst.). 
This mite is found upon the skin of dogs, hogs, goats,sheep, 
and probably of man, whereit producesscab. Theupper sur- 

Fig. 30.—Scah-mite of Fig. 31.—Scab-mite of the hog ,fe- 
the hog, male. Greatly en- male and egg. Greatly enlarged. 
larged. Original. Original. 
face of the female bears a number of triangular scales, which 
are not arranged in regular rows. The first row of scales 
commences behind the first spines upon the thorax. Head 
and legs are more hairy than in thecommonitch-mite. There 
are 6 sickle-shaped thorns upon the thorax, and 13 or 14 
pointed ones upon the back. 
The length of the male varies from 0.25 to 0.32 mm., 
