Mar. 2, 1908.] Agricultural Gazette of N.S.W, 217 



Diseases of Fowls. 



[Continued from i)age 58.] 



G. BRAUSHAW. 



The Chicken Mite. 



In an earlier Gazette tlie above pest was dealt with under the head of 

 " External parasites." The following report on the same subject has Ijeen 

 issued by the Iowa Experimental Station, U.S.A., and is the most exhaustive 

 on the subject yet published, and worth reproduction. The observations 

 were taken by Mr. J. J. Repp, V.M.D., and are as follow : — 



One of the most formidable enemies of chickens is unquestionably the chicken mite, 

 scientifically called Derinanyssus gallinc (Redi). My observations have demonstrated 

 that chickens infested with mites are exceedingly unprofitable. The cost of keeping 

 them is increased, and the income fi'om them is very much reduced ; indeed, when very 

 badly infested, they are totalh' incapacitated for performing work. 



The hen will cease laying. The ovaries undergo atrophy, and on autopsj- will be found 

 shrunken, and in a condition unsuitable for work. In several docks on which I made 

 ■observation, I found that egg production was greatly reduced or altogether prevented 

 during the spring and summer, when, under normal conditions, it would have been at its 

 height. 



Hatching hens will often either die on the nest as a result of the mite infestation, or 

 will leave their eggs, literallj* driven away by the vast hordes of mites wliich accumulate 

 upon them. In the case of three hens which thus died on the nest in one flock of 

 sixteen hens, I could not find any tissue change on post-mortem examination which 

 would account for death. There was, however, an anajmia, or impoverished condition 

 of the blood, such as would be produced by the sucking of the blood by the mites. 



The following is an extract from mj' autopsy record, which will serve for all three 

 ■cases : — "Subject, a light Brahma hen, found dead on the nest after sitting for nearly 

 three weeks. Her skin and feathers were swarming with mites, although there were a 

 few wdiite lice, the Mcnopon pdUiilum (Nitseh). The body was in fair flesh. The 

 ■digestive tract was nearly empty ; some oats were in the crop, and a small amount of 

 hard, dry fa?ces in ceca. In each ca?cum were found about a dozen worms — which I 

 identified as the Hvti'rakis papilloma (Bloch), one of the round worms of the chicken, but 

 they were not in sufficient numbers to exert any harmful efl'ect. The blood was 

 impoverished — a condition accounted for by the sucking of the blood by the mites. All 

 the organs wei-e normal, as far as could be determined by the naked eye. Death could 

 be accounted for only by the mite infestation. 



Another very important feature of the evil effects of mites is the injury they do to new- 

 born chicks. If the hen survives the ordeal to which she is subjected while hatching, 

 the young chicks are attacked by the mites in great swarms as soon as they leave the 

 protection of the shell, and, as a rule, the majority of them will succumb. I have known 

 the loss of new-bcjrn chicks from this cause U) reach 90 per cent. 



Chickens, both old and young, will become reduced in flesh, and lose the euergj' for 

 hunting and scratching which is so necessary to their welfare. The feathers will 

 become roughened and drop out, the head will become pale, and the chickens in every 

 way present an unthrifty and unhealthy appearance. Broilers which are being prepared 

 for market will not thrive well and will turn out in the end to be unprofitable ; in fact, a 

 loss to the owner. In addition to the sucking of blood, the mites reduce the vitality of 

 the fowls by biting them and disturljing their rest at night. The birds require more 

 food, and are at the same time incapable of converting it into tissue and energy as 

 Avould be done by iiealthy fowls. 



