29 



top of the highest tree in the orchard, into which it was lifted on 

 the end of a long light pole. The Haid was carried in a can and 

 applied by means of a hand force pump. More convenient ar- 

 rangements for work on a large scale might easily be devised, but 

 the foregoing answered our experimental purpose well. 



The spray was applied so thoroughly that we had no doubt, in 

 any case, that every apple was reached and bedewed by it. The finer 

 particles of water were so minute that they floated on the air and 

 were carried by the gentlest breeze, a rainbow forming readily in 

 the mist when thrown towards the sun. In fact, the spray thrown 

 by the adjustable nozzle was so delicate that at the height of the 

 tree-top it was sometimes scarcely visible, except when brought be- 

 tween us and the sun. Notwithstanding this minute subdivision of 

 the fluid, it evidently conveyed the Paris green, as the nozzle very 

 rarely clogged either with that or the London purple. The poisons 

 were kept suspended in the water by frequent stirring, and the 

 spray was thrown until the leaves began to drip. Applied in this 

 way we found about two gallons of fluid sufdcieut for a large apple- 

 tree. The time occupied averaged about four minutes to a tree. 



For the purpose of testing the results of the various applications 

 used, the fallen apples were picked up at short intervals and care- 

 fully examined one by one, the number affected by the codling 

 moth and by curculios being separately noted, and also those in- 

 jured in miscellaneous and undetermined ways. The number which 

 showed no traces of injury, belonging to each tree, was recorded 

 with the others, and these records were kept until the end of the 

 season. The ripened apples were then picl^ed, and theee also were 

 handled in the same manner, every apple from all the trees treated, 

 as well as from all the checks, having thus been individually exam- 

 ined, and in most cases cut in two. Something of the amount of 

 work done in this study may be inferred from the fact that the 

 number of apples thus separately scrutinized was 16,5'29. 



From the data thus obtained, calculations have been made, for 

 each collection and each experiment, of the number of apples af- 

 fected by the codling moth, by the curculios, and by all other 

 causes taken together, and of the ratio of these to the whole num- 

 ber of apples from each tree. The data thus obtained have been 

 carefully worked out, by comparison and cross-comparison, in a 

 manner the details of which I need not give you here, as they will 

 all be exhibited in the tables accompanying this paper. 



Before I begin any detailed account of the experiments, or state- 

 ment of the results, I wish to call especial attention to the excep- 

 tional circumstances of the year, and to the consequent peculiar 

 and provisional value of the conclusions based upon the season's 

 work. The crop of the year preceding had been very abundant 

 throughout the entire region around Champaign; and, in fact, the 

 apple orchards had averaged a fair yield at least, for some years in 

 succession, so that apple-feeding insects had had more than a me- 

 dmm opportunity for multiplication. When the spring opened this 

 season, they must, consequently, have been present in more than 

 average numbers. But the extremely short crop of this year neces- 

 sarily afforded them relatively little food, and hence what apples 



