206 



malathion (1 X)-ma] athion (1 X) groups. The control group had a mean mite 



count of 58.69 mites per bird. 



All treatments significantly reduced mite populations in 6 weeks, 



but Ravap reduced mite populations more dramatically than the other 



acaricides and in a shorter period of time. 



Efficacy of Two Synthetic Pyrethroid Compounds Against Northern Fowl 

 Mites on Laying Hens in Floor Pens 



Seventy-five 41-week-old White Leghorn laying hens at the University 

 of Florida Poultry Science Research Farm in Chipley, Florida, were 

 randomly divided into three groups of 25 hens each. Groups were housed 

 in pens measuring 3-65 by 3.65 m with wood shavings as floor litter. 

 Natural light was supplemented with morning and evening incandescent 

 lights so hens were exposed to 15 hr of light per day. A 16.9% protein 

 laying mash and water were provided free choice. Eggs were collected 

 da i 1 y by pen. 



The synthetic pyrethroid test materials, mixing procedures, and 

 application rates are shown in Table 59. Immediately following a pre- 

 treatment mite count on each hen, treatments were applied. A post- 

 treatment mite count was conducted 36 days later. Prior to treatment, 

 birds were leg-banded to identify them during the pre- and post- treatment 

 mite counts. 



Resul ts. Pre- and post-treatment field-estimated and converted 

 mite population counts and treatment means for each treatment are shown 

 in Table 60. Pre- and post-treatment field-estimated mite population 

 means are represented graphically in Figure k2. 



There were no significant differences between pretreatment mite 

 population means (Figure ^2), and the mite populations on the control 



