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they cease to lay, and, in the case of young birds, the growth is re- 

 tarded to such an extent that they never oecome fully developed ; 

 furthermore, they remain weak, and easily succumb to the mild 

 forms of bacterial disease. The blood-sucking parasites are periodic 

 in their attacks ; they do not live entirely on the bird, for after they 

 have engorged themselves they leave the chickens and hide in the 

 cracks and crevices of the houses ; for which reason a lathed and plas- 

 tered house is the best, as it affords no hiding place for the parasites. 

 Where this is not to be obtained, the next best thing must be used 

 and the efforts against the parasites increased. 



Of the blood-sucking parasites, probably none are so harmful 

 as the Argas americanus, more commonly known as the chicken 

 tick. It is an inhabitant of tropical America and is gradually ex- 

 tending northward. At the present time it is reported from various 

 parts of Texas as causing considerable loss to poultry raisers of that 

 State. It is usually about a quarter of an inch long. As a rule, the 

 parasites are very flat, unless they have recently fed; in the latter 

 event they assume a more rounded form. It will be noticed that the 

 head of the animal is entirely covered by the body. A hand lens 

 or an examination of the colored plate will show the back of the tick 

 to be covered with small pits which have an elevated margin, and 

 have a tendency to a symmetrical arrangement, but very often a 

 large pit on one side is represented by two or more small ones on the 

 other. The adults have four pairs of legs, but the young forms have 

 only three. 



The parasite was first described by Packard in the Sixth An- 

 nual Report of the United States Geological Survey of the Territories 

 for 1872. When not engorged with blood they are very flat, which 

 enables them to creep into very small cracks in boards and walls, a 

 fact which makes them very difficult to reach and emphasizes the 

 necessity of very thorough application of whatever means is adopted 

 for their eradication. They are nocturnal in their habits and are 

 capable of living a long time without nourishment. 



Of the remedies which have been used against the external par- 

 asites of chickens, none have proved so effectual as lime, alone or in 

 combination with other agents, such as carbolic acid, sulphur, or 

 corrosive sublimate. The method of making whitewash is too well 

 known to give description; it may be applied hot or cold, but its 

 efficacy is increased by its being applied hot. A good carbolic acid 

 and lime mixture may be made by mixing l 1 /^ pounds of lime and 

 one-quarter pound 100 per cent straw-colored carbolic acid to each 

 gallon of water. Corrosive sublimate is sometimes used in place of 

 carbolic acid but, on account of its poisonous properties, it is not to be 

 recommended. The various lime-wash mixtures are usually applied 

 with a brush, but where the area to be covered is very large it may be 

 used with a force pump. Whichever method is adopted, care must 

 be taken to fill all the cracks and crevices of the houses. As the pesta 

 against which the treatment is directed have a habit of falling to the 

 floor when disturbed, the floor also must be saturated with the mix- 

 ture ; where the floor is a wooden one it should be scrubbed with the 



