FORMULAS FOR DUSTING POWDERS 513 



fowls only, since the mercury is likely to prove dangerous to 

 chicks. 



Lice breathe through spiracles or pores in their sides, hence 

 they can be suffocated by stopping up these breathing tubes 

 with a fine powder. The instinct for a hen to take a dust bath 

 is nature's way to kill these pests. The most effective powder 

 for this purpose is that which contains a drying and burning 

 ingredient, or one giving off fumes. 



(Courtesy Wisconsin Experiment Station) 



Fig. 316.— Spraying the roosting compartments with an insecticide is part of 

 the sanitary schedule on a well-regulated poultry farm. 



A reliable home made powder can be mixed as follows: Add 

 an ounce of 90 per cent carbolic acid to a peck of sifted coal 

 ashes, mix thoroughly, and then add an equal quantity of tobacco 

 stem dust. 



Here is another recipe which has given satisfaction at the 

 Maine and Cornell Experiment Stations for a number of years: 

 Add one part crude carbolic acid to three parts gasoline, mix 

 these together carefully, and while stirring add enough plaster-of- 

 Paris to take up the moisture. When enough plaster has been' 

 33 



