The efficacy of lead arsenate in controlling the codling moth

Abstract

does not appear. First page follows. The investigator who undertakes an orchard spraying experiment for the purpose of determining the value of one or more elements in the spraying method of controlling the codling moth, Carpocapsa pomonella (Linn.), is confronted by a large number of unknown and uncontrollable factors which influence in various ways and degrees the results of his experiment. Conclusions arrived at under such conditions of experimentation are likely to be lacking in explicitness and accuracy, and they may sometimes be wholly erroneous. It is a well known fact that the vast literature on codling moth spraying is replete with contradictory experimental data, and discordant opinions and beliefs. A number of points of primary importance regarding this method of control have continued to remain largely in the realm of assumption and theory every since spraying was first employed in codling moth control nearly fifty years ago. Spraying tests have been confined almost without exception to orchard conditions. While assisting in some orchard experiments during the summer of 1917 to determine the relative merits of spraying and dusting with lead arsenate as a means of controlling this pest, I was impressed by the fact that so many variable factors were encountered as to render the resultant data of very doubtful value. Similar experiences met with in subsequent investigations and a study of the investigations of other entomologists emphasized the desirability of more accurate experimentation than could be accomplished under orchard conditions. It was during the late summer of 1920 that the idea was conceived of performing experiments with freshly hatched codling moth larvae in the laboratory. The work started that year was continued in a limited way in 1921, while fairly extensive studies were made in 1923 and 1924.