114 TRANSACTIONS OF THE ILLINOIS 



the damage on the tree not treated being forty-five per cent, and 

 that upon the sprayed tree twenty-two per cent. The exceedingly 

 low ratio of injury at the beginning of the season — a phenomenon 

 which will be apparent throughout all the diagrams for this year — 

 have, of course, the explanation already given; viz., that the tree 

 set very full in spring, and early cast a great quantity of their sur- 

 plus apples. 



A curious drop in the bands of both check and experimental 

 trees for the observation of September 8, probably marks an interval 

 between second and third broods, similar to that already noticed be- 

 tween the first and second of last year.* 



Of the apples borne by these trees, we examined 2.260 from 

 the check, and 1,680 from the tree sprayed with poison. The num- 

 ber of apples on these and several other of the trees was so great that, 

 towards the end of the season, we did not examine them all, but 

 stopped when we demonstrated that we had a fair average of the 

 whole. 



The increased benefit, from a second spraying, is made evident 

 by the greater difference in length of the bands representing the two 

 trees on Diagram IV, as compared with those of the preceding chart, 

 although the ratio of benefit to fallen fruit is not very different, the 

 fifty-two per cent, benefit to the picked apples, once sprayed, becomes 

 eighty-four per cent, after the second spraying. Curiously, the third 

 spraying (Diagram V) seems to have been without appreciable effect, 

 neither the picked nor the fallen fruit, from the tree thrice treated, 

 being any less wonny than that from the tree sprayed but twice. 

 The same fact is apparent upon an examination of the other two 

 trees, sprayed respectively twice and thrice. 



The respective advantages of spraying once and twice are more 

 fully represented on Diagram VI, when the longer open bands are 

 composites, obtained by combining the numbers from four check 

 trees; the longer solid ones are derived from both trees oncf sprayed, 

 and the shorter solid ones are made up from the ratios of two trees 

 sprayed twice. 



The most remarkable exhibition of benefit, is that of Diagram 

 VII, derived from a single tree, — the Vandevere variety — as com- 

 pared with its selected check. The bands of damage for the latter 

 range, as will be seen, from naught to sixty-three per cent., the 

 general average for the fallen fruit being forty-seven per cent., and 

 for the picked apples forty-three per cent.; while the bands for the 

 treated tree vary only from zero to twelve per cent., the total fallen 



*0n the 31st August the larvae were reported by the assist-inls engaged on the work as 

 " mostly full grown," and Septemljur 8, hs mostly full grown, but with spcfimens oecasionally 

 occurring that were not more than half size. September 2U, on ihe other hand, when 4,146 ap- 

 ples were examined, a very large percentage (three-fourths to tive-sixths) of the apples con- 

 tained very small larvae, many of them near the blos-iom end and appirently jiisi entering, the 

 others being all full grown. October 4, flaally, many of tlie ai>ples contained very young larv», 

 although the majority were one-third to two-thirds grown. The notes of the assistants are sup- 

 ported bv alcoholic specimens. 



