EXTERNAL PARASITES 



73 



SARCOPTES MUTANS 



Description.— This parasite is one of the same family of scab 

 parasites that infest horses, cattle, hogs, sheep and cats. That 

 particular branch of the family affecting chickens is distinguished 

 by calling it "variety gallinge"; gallinte being a Latin word mean- 

 ing "of the chicken." Owing to the small size of the parasite, it 

 is often called a mite. Fig. 27 illustrates the parasite magnified 

 100 times; the actual size of the parasite is shown by the small 

 dot in the square at the right side of the drawing. In the drawing 

 it will be noted that the legs are short and strong and that its 

 mouth parts are arranged for biting the skin. They subsist upon 

 serum that exudes at the point of attack and forms scales or scabs 

 (see Fig. 28). 



Life History. — The female lays her eggs under the scabs, where 

 in about ten days they hatch, if conditions are favorable. The 

 larvae or young mites are provided with only three pairs of legs and 

 are not provided with sexual organs. They pass through several 

 molts and are finally developed into the adult stage, and at that 

 time are provided with four pairs of legs, with genital organs and 

 are sexually mature. 



The tearing off of the scabs favors the escape of the parasites, 

 which in w-arm weather may live in the filth, roosts, nests or other 

 parts of the building for at least thirty days, and may in that time 

 find their w^ay upon other birds and infest them, causing in turn 

 scaly legs on the new host. Thus birds become affected by being 

 placed in infested quarters, or by having an infested bird placed in 

 the same lot or enclosure as at poultry shows, should any of the 

 birds there be infested. 



Symptoms. — This parasite attacks chickens, turkeys and 

 cage birds, but the writer has not observed it infesting ducks 

 or geese. It always attacks the unfeath- 

 ered portion of the legs above the foot, and 

 often the upper portion of the toes. The 

 minute parasite crawls under the scales of 

 the legs and there irritates the tissue by 

 attacking it with its strong mouth parts. 

 As a result of this irritation a vesicle or 

 small blister appears. The blister is prac- 

 tically microscopic in size and later rup- 

 tures. This small Cjuantity of serum dries 

 and forms a minute scale. These scales 

 accumulate until later large, scaly masses 

 appear. Fig. 28 is a good illustration of 

 this condition. 



The parasites can be found as minute 

 white specks in the serum between the 

 scab and leg. Both legs are usually af- 

 fected at the same time. Itching is pres- 

 ent and the birds may pick at the affected parts. Itching is 

 more intense at night. The birds may become weak, stop laying 

 and even die from the effects of the irritation and loss of rest. 



Fig. 27. Sarcoptes 

 M u T A N s. Variety 

 Gallinae. 



A, mouth parts; 1>, 

 short, stubby legs; C, 

 dot indicating actual 

 size of parasite. 



