33 



observed is not necessarily an indication of the severity of the infes- 

 tation (J. F. Butler, personal aomrm,m.iaation) . The way to determine 

 the severity of infestation is to directly examine the suspected fowl 

 and check for the symptomology described above. Restlessness at night 

 due to irritation may be indicative of northern fowl mite infestation 

 (Petrak, 1969), but again, positive determination of infestation can 

 best be made by examination of birds. 

 Latent effects of northern fowl mite infestation 



Death of the bird host is often associated with severe northern fowl 

 mite infestations and could be termed the utmost patent effect. Death, 

 however, is due to the results of certain latent effects. Cameron 

 (1938) blamed loss of vitality and death on loss of blood. Al thougn it 

 is not known whether blood loss produced an anemia, death in severe 

 cases has been attributed to anemia which resulted from exsangu i nat ion 

 (Metcalf et al., 1962; Petrak, 1969; Koehler, 1977; Matthysse et al., 

 197*0. Recent studies have shown that this is not necessarily the case. 

 Loomis et al. (1970) worked with hens having mite populations from light 

 to severe and anemia was not shown to be a symptom of heavy mite infes- 

 tations. DeVaney et al. (1977) found no anemia in roosters due to mite 

 popul at ions . 



Weight loss has also been attributed to severe northern fowl mite 

 infestation (Anonymous, 1967; Koehler, 1977). DeVaney et al. (1977) 

 found no significant differences in the weights of roosters due to mite 

 populations. In another study weights of two groups of hens did not 

 change significantly due to mite infestations (DeVaney, 1979). 



