EXTERNAL PARASITES 



45 



The tearing off of the scabs favors the escape of the para- 

 sites, which in warm 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 way 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, tur- 

 keys and cage birds, but the writer has not ob- 

 served it infesting _ . ~ « 

 ducks or geese. It al- 

 ways attacks the un- 

 feathered 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 attack- 

 ing it with its strong 

 mouth parts. As a 

 result of this irrita- 

 tion a vesicle or small 

 blister appears. The 

 blister is practically 

 microscopic in size 

 and later ruptures. 

 This small quantity 

 of serum dries and forms a minute scale. These 

 scales accumulate until later large scaly masses 

 appear. Fig. 11 is a good illustration of this 

 condition. 



The parasites can be found as minute whitg 

 specks in the serum between the scab and leg. 

 Both legs are usually affected at the same time. 



Fig. II. Scaly Legs (Scabies) 



A, Mass of scabs due to dried serum 



that exudes from injured part. B, 



scale of leg forced up and out of 



place by accumulation of dried serum. 



