142 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



weather. Two pounds of adhesive material to each 25 pounds of poison 

 and diluents may be given as an average proportion. 



The principles that should be followed in the dry application are, to 

 mix the poison thoroughly with the diluents, and to apply the mixture 

 as evenly and slightly as possible on the plants when the worms are 

 still very young. The best time of the day to apply the poison is early 

 in the morning when the plants are still wet with dew. Dry and windy 

 weather is unfavorable to an even and economical application. 



Wet APPLICATION. — This is a much simpler process than the dry 

 application. The required amount of poison is stirred up in a certain 

 amount of water, the liquid being then evenly and economically dis- 

 tributed upon the leaves of the plants. The large series of machines 

 invented for this purpose accomplish this in a more or less perfect way, 

 the water being broken up into a very fine spray. Most of the arseni- 

 cal poisons not being soluble in water must be kept suspended by stir- 

 ring, but this difficulty is easily overcome either by the employment of 

 an additional hand to keep the water stirred up or by adding to the 

 various pumps with which the poison is distributed a simple self-acting 

 lever inside of the barrel or other vessel containing it. This, together 

 with the motion of the pump, is sufficient to prevent settlement. It 

 pays to add two or three pounds of flour or starch to each barrel of the 

 poison mixture, not only because of the greater adhesiveness which they 

 give to the poison (a very desirable object, especially in wet weather), 

 but because, by their color, they help to indicate the quantity that 

 has been distributed, and, also, because they serve to keep the poisons 

 suspended in the water. In using flQur it will be found advisable to 

 mix it first in a bucketful of water and allow it to remain until it sours, 

 the object being to prevent it from forming lumps. Another ingredient 

 that may be advantageously added is very finely sifted wood ashes in 

 such quantity as not to interfere with the distribution of the poison. 

 They tend to 4essen the caustic action of the poison on the plant. The 

 most important point in wet applications is to have a good supply of 

 water handy and readily accessible near the field, and it should be as 

 free as possible from impurities. 



The best time for applying wet poisons is in the afternoon, or at 

 least after the dew has disappeared. Dry weather is the most favora- 

 ble, while in rainy weather the wet application, especially from above, 

 should not be attempted. 



The relative advantages and disadvantages of the two methods of 

 applying arsenical poisons may be briefly summed up as follows : The 

 wet application is by far the cheaper so long as we are obliged to use 

 a large amount of costly diluents in the dry application. It is also the 

 quickest method, as a liquid spray can be thrown over more rows of 

 cotton than a dry powder. During dry weather the wet application 

 is preferable, while in rainy weather the dry application may be found 

 more advantageous or even necessary, not only because its effect is less 



