SCABIES OF CATTLE, OR MANGE. 915 



are 



will the cattle mite attack sheep or other animals. The itch mites 

 found to be very numerous upon affected cattle, and a very small quantity 

 of debris from an actively infested area of the skin will often reveal a 

 surprisingly large number of the parasites. These mites may be removed 

 from an animal and retain their vitality for a long time. Specimens have 

 been collected and kept in small glass bottles in the laboratory at the 

 ordinary temperature of the room during the winter months, varying 

 from 45° F. during the night to 80° F. during the day, which would live 

 and remain active from eight to eleven days. Exposure to bright sun- 

 light, however, would kill most of the mites in a few hours. 



Sckbies does not appear to affect cattle while they are doing well on 

 grass, nor to attack those in good condition over three years old. The 

 animals which suffer most are calves, yeariings, and two-year-olds, and 

 those in poor condition. The first symptom of the disease is usually 

 an intense itching of the skin about the neck or shoulders, which ex- 

 tends more or less rapidly, depending largely upon the health and vigor 

 of the animal, along the back and sides and down the outside of the legs, 

 but does not usually affect the inside of the legs nor the skin of the 

 abdomen. 



The other variety of this parasite which produces mange in cattle is 

 the Symbiotes. This is known as Symbiotic mange, or tail mange. It 

 remains generally localized upon the depressions on the back part of the 

 croup and at the base of the tail. It may, however, extend over the 

 whole surface of the body if the treatment of the disease and care of the 

 affected animal are neglected. These cases, however, are rare. Foot mange 

 is also exceptional in cattle. Tail mange has almost no spreading ten- 

 dency, and its contagiousness is hardly noticeable. It yields readily to 

 treatment, and any remedy that will destroy the activity of the parasite 

 producing the Psoroptic, or common form of mange, will readily kill 

 that causing the Symbiotic, or tail mange. It is possible for the different 

 morbid conditions produced by these two varieties of parasites to exist 

 in the same animal at the same time. 



II. Form and Life History of the Scab Parasite. 



The Psoroptes, the first variety referred to, live upon the surface of 

 the skin, adhere to it, and suck the blood and lymph of the skin by means 

 of their mouth organs, producing a more or less intense inflammation 

 through the numerous stings which they inflict. This species is character- 

 ized by its relatively greater size. Its general form is rounded or egg- 

 shaped. It can be seen with the naked eye upon dark surfaces, and is 

 very easily seen with the help of a magnifying glass. The head is elon- 

 gated and pointed. The jaws are long, straight, and stinging. The legs 

 are very long. The sucking cups, which are tulip or trumpet-shaped, are 



