144 EEPOET 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



chine and the labor. Both of the last two items are extremely variable, 

 and it is difficult to get at the average cost. One of the improved 

 sprinklers will cost, on an average, say, $15, and will last for several 

 seasons with but little expenditure for repairs. Two hands are neces- 

 sary to operate the machine. One hundred acres of cotton can be 

 poisoned in a day by these two men with one machine, 16 pounds of 

 Paris green, and (not absolutely necessary) a small amount of flour and 

 ashes. 



This dry method of applying Paris green has proved satisfactory 

 under the conditions already referred to whenever a genuine article 

 has been obtained and properly applied. Reported cases of failure mnst 

 be attributed to adulterated poison, or to the use during very wet 

 weather of ingredients of inferior quality. The proportion of the green 

 to the ingredients actually in use in the South varies from 1 pound of 

 the green to 20 pounds of ingredients, to 1 pound of green to about 35 

 pounds of ingredients, the stronger mixture being generally adopted in 

 Texas, the weaker in the more eastern portion of the cotton belt. This 

 great difference is partially explained by the fact that the mixture is as 

 a rule more economically applied in Texas than further east. The origi- 

 nal idea was to distribute 1 pound of the green over one acre of cotton 

 of average size, and by a very slow and careful manipulation of the 

 sieves it is indeed barely possible to accomplish this satisfactorily if 20 

 pounds of ingredients are added. Practically, however, the amount of 

 the mixture used per acre always exceeds 30 pounds, and often reaches 

 50 pounds or even more. This great waste is the necessary consequence 

 cMf the imperfect implements that have been employed so far, and par- 

 tially also of the carelessness of the hands. The small tin sieves so ex- 

 tensively used in the cane -brake region of Alabama are especially waste- 

 ful in the distribution of the mixture, and one barrel (almost 200 pounds) 

 is, on some plantations, not expected to go over much more than three 

 acres. That 1 pound of the green to 30 pounds of diluents applied at 

 the rate of not more than 20 pounds to the acre is efficient has been 

 proved by actual experience over and over again, and all stronger ad- 

 mixtures of the green should, therefore, be abandoned. But in every 

 application of this mixture during dry weather another point of still 

 greater importance can be learned : Wherever the mixture is applied 

 very slightly, so as to be a mere dusting of the leaves, it is fully as effi- 

 cient as where it thickly covers the plant. One of the chief aims we 

 have had in mind has been to ascertain by experiment the minimum 

 quantity of the poison that could advantageously be used, and Mr. 

 Schwarz was intrusted with experiments in this direction. He reports 

 as folio ws- 



"'Mini7mc7n quantity of Paris green. — That the method of applying dry 

 poisons by means of common bread-sieves, and still more by means of 

 small tin sieves, is a very wasteful one, needs no further remark, and a 



