69 



Compounds were mixed using formulas as described in Neal (1974) 

 and applied to run-off with hand-held trigger-action sprayers. Nozzles 

 were adjusted to produce a cone 15 to 20 cm in diameter when the sprayers 

 were held 31 cm from the panel surface. Sprayers were calibrated with 

 graduated cylinders. 



After insecticides were applied and allowed to dry, panels were 

 hung in houses 1 through k at the tilling site, and the guttering was 

 attached. 

 Evaluation of Northern Fowl Mite Populations 



Field estimates. Field evaluation of mite populations on individual 

 birds required two workers. The first worker, the handler, suspended the 

 birds by their feet with the birds' breasts facing the second worker, the 

 counter (Figures 8 and 9). The counter examined the birds, starting at 

 the tip of the keel bone, working caudal ly to the vent area, and over 

 the dorsal portion of the tail. In severe cases, mites were found on 

 both legs down to the shanks, and more anteriorly than the tip of the 

 keel bone. 



Counts were designated as follows: 



No mi tes seen 



From 1 to 10 mites Counted individually 



From 10 to 100 mites Counted by 5's, i.e. 1 5, 20, 25, etc. 



From 100 to 200 mites Counted by 50' s 



Over 200 mites Counted by 100's 



Counters and handlers never interchanged. Counters identified the 

 birds and recorded the mite counts after birds were examined. Counters 

 frequently double-checked each other to be sure that counts were uniform. 



Calculation of a conversion factor. An attempt was made to correlate 

 field-estimated mite populations with mite populations actually present 

 on hens by extracting field-estimated mite populations from hens with a 



