592 



DISEASES OF THE SKIN. 



2. Ticks are insects which have the same form as theacarus, but 

 they are larger. They are found in woods, in grass ; they become 

 iixed upon the skin of domestic animals, of which they suck the 

 blood. We recognize the tick of the dog (Ixodes ricinus), which 

 affects the dog, ox, and sheep : the reticulated ixode {Ixodes reticu-^ 

 latus)^ a parasite of the ox and sheep), and the American ixocl(' 

 {Ixodes Americanus), which attacks the horse in certain parts of the 

 New World. These insects may be removed by means of common 

 oil, cresol, or carbolated oil ; by essences (turpentine, anise, cumin, 

 fennel, etc.). It is not proper to tear them out ; when this is done 

 the head of the parasite remains in the substance of the derma. 



3. HiPPOBOSC^ (Pupipares) are observed upon the horse {Hip- 

 pobosca equina) and the sheep [Melophagus ovinus). The hippo- 

 boscse of the horse are located upon the base of the tail, in the 

 neighborhood of the anus or upon the lower aspect of the abdo- 

 men; they irritate the animals more by their rapid movements 

 than by their bites. The melophages are particularly found upon 

 sheep going to pasture ; they suck the blood and produce a very 

 intense cutaneous irritation ; the animals rub themselves, they bite 

 the fleece and spoil it ; the wool is often colored green from the ex- 

 crements of these parasites. The agents to be used to combat mel- 

 ophages are decoctions of tobacco, lotions with cresol or carbol solu- 

 tions, and applications of mercurial ointment (3 to 4 grammes per 

 head) along the back and neck. The animals must be shorn be- 

 forehand. In experiments instituted to determine the degree of 

 toxicity of cresol against the Melophagus ovinus, Frohner has 

 obtained the following results : Adult parasites are killed within 

 ten to twelve minutes by a few drops of cresol solution at 3 per 

 cent., and in fifteen to twenty minutes with a solution of 0.51 per 

 cent. ; mangy sheep carrying many melophages are entirely freed 

 by a single bath of cresol at 2.5 per cent. 



4. Dermanyssus locates in preference upon chickens, pigeons, 

 swallows, and house birds; they lodge also in poultry aviaries 

 and in cages. They are of a blood-red or red-brown color. Dur- 

 ing the night they overrun any mammals within their reach (oxen, 

 horses, dogs, and cats), and occasion intense itching, even eruptions. 

 They are sometimes found in considerable numbers under blankets 

 (Trasbot). In the horse Steinbach observed a dermanyssic erup- 

 tion similar to mange; the skin was covered with scabs, which 

 were separated by narrow crevices ; the parasites nested in the front 



