358 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 15 



of larvae, all about the same age, are present, it would seem that nearly 

 all might be killed by a single spray at the time of hatching ; but at this 

 time rains are frequent and new leaves are being formed rapidly, so 

 that control is actually more difficult then later. Complete control would 

 necessitate keeping all foliage continuously coated with poison for 

 several weeks. Before experiments were conducted, it seemed doubtful 

 if enough larvae could be killed to reduce injury ; but it was found that 

 a single spray application gives the leaf-roller a substantial check and 

 benefits the plants decidedly if they are being injured. 



Results 

 The tests made by the writer were all on plots of less than one-half 

 acre. Since the point to be tested was whether any arsenical would 

 give satisfactory control, dry lead arsenate at the rate of 2 pounds to 

 50 gallons of water was applied, using a compressed-air sprayet*. Half 

 the strength would probably do just as well. In all except the first 

 two tests, resin soap was used as a "spreader" and "sticker." In each 

 case equal sprayed and unsprayed areas were counted over. Some 

 difficulty was encountered in finding infestation severe enough for 

 experiments. In plots 1, 2 and 4 some larvae were present at spraying 

 time but had disappeared before counts were made. 



Table of Results 



A weighted average of the above gives 63% control from a single spray. 

 The only large-scale spraying against the leaf -roller observed by the 

 writer was that done in 1918 by Mr. F. W. Dixon at Holton, Kans., on 

 about 60 acres of strawberries on his nursery farm. Leaf -rollers were 

 first noticed in numbers in the fall of 1917, and began to be very injurious 

 the following spring. Injury was aggravated by drouth, which was also 



