THE FRUIT-TREE LEAF-ROLLER. 107 



estimated that the tobacco mixture applied May 2 and 3 destroyed 

 about 50 per cent of the worms then on the trees. Plat III, which 

 received two applications of the combination spray, showed no better 

 results than on Plat IV, which received only arsenate of lead for the 

 second treatment. Plat VI (Paris green alone) showed a slight 

 improvement over Plats I (arsenate of lead 3:50) and II (arsenate of 

 lead 3:50 plus 4 ounces Paris green). Plat V, which was sprayed 

 with arsenate of zinc at the rate of 1 pound to 50 gallons of water, 

 gave disappointing results, as it not only failed to destroy the larvae 

 hi goodly numbers but it seriously burned the foliage. The arsenical 

 injury to the foliage could, however, have been prevented if lime 

 had been added. An increased strength of this arsenical would no 

 doubt have been more effective. On Plats VII, VIII, and IX, where 

 40 per cent nicotine solution alone was used, the benefit from spray- 

 ing was considerably less. Plat VII of these plats gave the best 

 results. On the day after the spraying, by carefully counting the 

 number of dead larvae as compared with the living ones found on the 

 trees, it was found that about 55 per cent of the larvae were killed 

 by the spray. On Plats VIII and IX not more than 25 per cent of 

 the larvae were killed. These plats, however, were sprayed a week 

 later than Plat VII, and the difference in results was probably due 

 to the fact that the worms at that time were more resistant to the 

 tobacco mixture and that it was much more difficult to reach them 

 in the rolled-up leaves. 



It will be noted in comparing the sprayed plats with the unsprayed 

 plat as to the amount of injury to the fruit alone that there is much 

 in favor of spraying. The benefit for each plat over the check plat 

 is shown in percentages as follows : Plat I, 78 ; Plat II, 78 ; Plat III, 

 83; Plat IV, 83; Plat V, 73; Plat VI, 80; Plat VII, 73; Plat VIII, 

 83; Plat IX, 83. The difference in condition of foliage must not be 

 lost sight of in determining the benefit of spraying. The check trees 

 were practically defoliated, while the sprayed trees retained their 

 foliage throughout the season and were enabled to develop fruit buds 

 for the following season. 



Although there is much in favor of spraying with arsenicals, alone 

 or in combination with tobacco, they have not given entire satisfaction, 



LIGHT TRAPS. 



The writer had occasion to observe many rights used as traps to 

 catch the moths of the leaf -roller at Canon City, Colo., during the 

 season of 1912. The use of these traps was not advocated, but many 

 orchardists were of the opinion that a decided benefit would be 

 derived if enough fights were placed in the orchard, as the moths 

 were very readily attracted to them. Such orchards were examined 



