261 



Egg production levels could not be correlated with mite infestation 

 levels (Figure 45; . Perhaps hen performance during the experiment was 

 not related to mite infestation levels that existed at the time of the 

 experiment, but to mite infestation levels that existed at some time 

 prior to the experimental period. Hens infested with mites by DeVaney 

 (1978) at different points in the laying cycle produced eggs at signifi- 

 cantly lower levels 6 to 8 weeks following the onset of infestation. 

 Hen performance during the experiment at Chipley may also have been due 

 to the effect of mite infestation levels over time. 



During the experiment, mite populations on untreated hens fluc- 

 tuated as they must have done prior to and following the end of the 

 experiment. Therefore, inferences made about egg production and mite 

 infestation rates may not be entirely correct since the entire picture 

 is not known. Studies providing for long-term monitoring of egg pro- 

 duction and mite infestation rates should provide the data necessary to 

 determine whether or not a correlation does exist between the two. 



Whether it is statistically significant or not, a \% decrease in 

 egg production can be costly to a poultry farm owner (R. H. Harms, 

 personal aomrnuniaation) . If a hen lays an average of 240 eggs per year 

 with a current wholesale value of 5 cents per dozen, a }% drop in pro- 

 duction for just 1 day can cost the owner of a 35,000-bird flock $350. 

 The first week after birds were treated in Chipley, the production level 

 of the treated birds was \% lower than the control birds. One week 

 later, however, treated birds had increased production by \ .5% and were 

 again laying at a numerically higher rate than the controls. After the 

 second treatment, production in the treated birds dropped by 0.64%. 



