DISEASES OF CATTLE 377 



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 

 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 they are seen on the four pairs of legs ; in the female, upon the 

 first, second, and fourth pairs only. In the immature form the 

 Psoroptes 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 represented by mandibles or jaws. The skin sur- 

 face 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 under- 

 gone 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 remam alive from two to four 

 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 

 movements 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; consequently 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 Psoroptic or common form ; but in neither variety is the con- 

 tagion transmitted 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, there- 

 fore, seem important to refer to this form of mange parasite and 



