is characterized 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 elongated and pointed. The jaws are long, straight, and 

 stinging. The legs are very long. The sucking cups, which are tulip 

 or trumpet-shaped, are carried on the legs. In the male the}' are seen 

 on the four pairs of legs; in the female, upon the first, second, and 

 fourth pairs only. In their immature form the Psaroptes or common 

 mange mites have three pairs of legs, while in the adult state they 

 possess four. The latter with five joints are fitted with suction cups 

 covered with fine hair and armed with claws or hooks. The head, 

 thorax, and abdomen are not separated. The mouth parts are repre- 

 sented by mandibles or jaws. The skin surface is covered with scales, 

 hair, spikes, or silky hair, etc. 



Females, which are larger than males, lay from 20 to 24 eggs; at 

 the end of 4 to 7 days the larvae come out and, after having undergone 

 3 or 4 changes, arrive at the stage of reproduction from the fourteenth 

 to the seventeenth day. If exposed to damp air, or placed upon wet 

 manure, the mange mites continue to live from 6 to 8 weeks. Upon 

 damp ground the eggs remain alive from 2 to 4 weeks. In a dry place 

 they lose their vitality after 4 to 6 days. Moderate heat is favorable 

 to their vitality and to the hatching of the mites. 



In warm places under cover, and during the summer, their move- 

 ments are more active and they multiply more rapidly than under the 

 opposite condition. It has been estimated that- one female alone may 

 produce 1,500,000 individuals in 90 days. 



Each animal species has its specific mange parasites, or mites; conse- 

 quently the expression "mange" must necessarily be incomplete unless 

 the variety of the parasite is indicated. Thus, of the Psoroptic variety, 

 we have the ox mange mites, the horse mange mites, and the sheep 

 mange mites. 



In each of these animals we also have the Symbiotic, or tail, mange, 

 and in each the variety would be designated as in the case of the Pso- 

 roptic or common form; but in neither variety is the contagion trans- 

 mitted from one species of animal to the other. The tail -mange mites 

 live especially upon the surface of the skin of the extremities, and 

 exist in scabs in the outer layer of the skin. Their outlines are visible 

 to the naked eye. The head is short and wider than it is long. The 

 body is slightly egg-shaped and notched upon the outer edge. The 

 legs are long and the sucking cups are shaped like a Roman shield, and 

 are distributed in both the male and female, as in the case of the same 

 organs on the legs of the common mange mites. 



Sarcoptic mange is a more serious disease than either of those already 

 described, but is not common to cattle. It would not, therefore, seem 



80856 Bull, ir.2 15 2 



