HEALTH AND DISEASE OF POULTRY 557 



called Dermanyssus gallinae Redi. Observations have demonstrated 

 that chickens infested with mites are exceedingly unprofitable. The 

 cost of keeping them is increased and the income from them is very 

 much reduced. Indeed, when very badly infested they are totally 

 incapacitated for performing work. 



The hens will cease laying. The ovaries undergo atrophy and 

 on autopsy will be found shrunken and in a condition unsuitable 

 for work. In several flocks on which observations were made, it was 

 found that egg production was greatly reduced or altogether pre- 

 vented during the spring and summer when, under normal condi- 

 tions 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, literally driven away by 

 the vast hordes of mites which accumulate upon them. In case of 

 three hens which thus died upon the nest in one flock of sixteen hens, 

 no tissue change could be found on post-mortem examination which 

 would account for death. There was, however, an anemia, or impov- 

 erished condition of the blood, such as would be produced by the 

 sucking of the blood by the mites. Following is an abstract from 

 autopsy records. 



Subject : Light Brahma hen found dead on the nest after sitting 

 nearly three weeks. Skin and feathers swarming with mites. Also 

 a few white lice, the Menopon pallidum Nitsch. Body in fair flesh. 

 The digestive tract was almost empty ; some oats in the crop ; a small 

 amount of hard, dry, feces in ceca. In each cecum were found about 

 a dozen worms w r hich were identified as the Heterakis papillosa Bloch, 

 one of the round worms of the chicken, but these were not in suffi- 

 cient number to exert any harmful effect. The blood w r as impover- 

 ished, a condition accounted for by the sucking of the blood by the 

 mites. All the organs were normal so 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 newborn chicks. If the hen survives the ordeal 

 to which she is subjected while hatching, the young chicks are at- 

 tacked by the mites in great swarms as soon as they leave the protec- 

 tion of the shell, and, as a rule, the majority of them will succumb. 

 The loss of newborn chicks from this cause has been known to reach 

 ninety per cent. 



Chickens, both old and young, w r ill become reduced in flesh and 

 lose the energy for hunting and scratching w ? hich is so necessary to 

 their welfare. Their feathers will become roughened and drop out, 

 the head will become pale and the chicken in every way present an 

 unthrifty and unhealthy appearance. Broilers which are being pre- 

 pared for market wall not thrive well and will turn put in the end to 

 be unprofitable, in fact a loss to the owner. In addition to the suck- 

 ing of blood the mites further reduce the vitality of the fowls by 

 biting them and disturbing their rest at night. They require more 

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

 and energy as would be done by a healthy fowl. 



