200 



All three hens in each cage were examined initially, and the one having 

 the highest mite population was selected as the test animal. For identi- 

 fication purposes, test animals were marked on the wing feathers with a 

 water-proof black magic marker. A total of 480 hens was used in the 

 experiment. 



The formulations and mixing instructions, test concentrations and 

 application rates for the acaricides tested are shown in Table 56. The 

 treatment schedule is shown in Table 57- Malathion in treatment 1 was 

 incorrectly mixed and applied before the error was discovered, as 

 frequently occurs on commercial poultry operations. A second malathion 

 treatment was added with malathion mixed at the proper concentration. 

 Both treatments were maintained throughout the experiment. 



On the day before the initial application of acaricides, a mite 

 precount was made. Two weeks after making the precount, a second mite 

 count was made. The following day, the second treatment was applied. 

 Two weeks after making the second mite count, a third count was made, 

 followed by a third treatment the following day. Two weeks after the 

 third mite count was made, a fourth and final count was made. 



Resu Its. Weekly mite population means and converted population 

 means are shown for each treatment in Table 58. A plot of mite popula- 

 tion means per hen by treatment is shown in Figure k\ . 



There were significant differences between precount mite population 

 means in the treatment groups (Table 58). This was unimportant, however, 

 because the precount mite mean for the control group was in between the 

 highest and lowest precount mite means, and because the final mite 

 counts for all groups were significantly lower than the precount of the 

 control group. 



