212 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



Our experiments show clearly that, while dusting has possibilities, it 

 is not wise with our present knowledge and experience to encourage 

 too great expectations as to the practicability of combating comjnon 

 sucking insects by this system of treatment. Growers who possess 

 dusting machinery and do not consider present prices for contact 

 insecticides prohibitive, might well conduct an experim.ent against the 

 apple redbug. To attempt very large operations against other species 

 of sucking insects would expose the growers to the risk of great expendi- 

 tures for materials and large losses in fruit yields through inefficient 

 control. 



If the data make one point clear it is that dusting for sucking insects 

 is in its first phase. While many failures have been noted in our experi- 

 ments, we should be ignoring the historv^ of sc^ientific progress if we relied 

 too much on early negative indications. The conservative as well as 

 the constructive view to take is that conditions have passed the stage 

 where dusting is considered wholly im.practicable to one where it may 

 be regarded as having possibilities under certain conditions. It remains 

 to be seen whether this S3-stem. of treatment will enter the realm of 

 practical fulfillment of all the requirements and needs of the commer- 

 cial orchard. It will take time and money, but it is well worth doing and 

 needs to be taken up by those with special aptitude and necessary funds 

 and equipment. 



Improvements in Machine Construction 

 The conspicuous results obtained by dusting are speed of operation 

 and economy in labor. It is presumed that dusting machinery is in the 

 experimental stage and, if so, improvements will unquestionably be 

 made that will meet the requirements of different field crops and various 

 bush and tree fruits. It is also net unreasonable to hope that for the 

 treatment of large trees outfits will be available which will insure 

 satisfactory distribution of materials without sacrificing speed. 



With such pests as redbugs and aphids, effective results will depend 

 on the thorough coating of the insects. In dusting large trees it has 

 been difficult to obtain satisfactory control without incurring large ex- 

 pense for dosage, which appears excessive in comparison with the cost 

 of labor or for like materials used in spraying. In considering the items 

 that enter into this expense, the fact stands out clearly that contact 

 insecticides in powder form now prepared and sold by ccrrm-ercial 

 companies are expensive and almost prohibitive for large operations. 

 On the other hand, with existing types of orchard dusting outfits there 

 is danger of applying excessive amounts to insure thorough treatment, 

 and ever}' pound in excess of actual requirements for effective work 

 multiplies rapidly the cost of the operation. It is evident, then, that 



