88 



The weather was favorable to the experiment. The insecti- 

 cides were applied on the afternoon of March 20, and a slow fine 

 rain began at S p. m. of the same day and continued until nine 

 o'clock and for an unknown time into the night. Rain fell in a 

 continuous drizzle, broken by showers, the whole of the following- 

 day, March 21, to an amount estimated b}^ Mr. Titus at more than 

 thirty gallons per tree. 



The temperature of the 20th was 34 at 7 a. m. and 57 at noon; 

 that of the 21st was 44" at 7 a. m. and 52" at noon, the wind from 

 the southeast both days. Observations on this experiment contin- 

 ued only until the 2Sth, but counts of the scales were made daily 

 up to that time — 3,000 scales for the four experimental trees, and 

 2,050, for the two checks. 



In this small experiment no differences of any significance 

 were made out in the action of the insecticides, the total general 

 effect being the destruction of approximately 95 per cent, of the 

 scales at the end of five days, and variations from this average in 

 the individual trees being too slight to take into account. So far as 

 any conclusion can be drawn from an experiment on so small a 

 scale, we can only infer that a rainfall such as described, occurring 

 at the time of the insecticide treatment, would have no appreciable 

 eflfect on the action of either of the washes. 



Effects of Kain and Water Sprav.s in washing off Dead 



Scales. 

 Noticing that many scales were loosened and washed away after 

 insecticide treatment of the trees, Mr. Titus made some careful 

 counts from day to day of selected lots of scales on the experimental 

 trees to determine the circumstances and the ratio of their diminu- 

 tion in numbers. Selecting, for example, a definite part of a branch, 

 counting a hundred scales on it when the insecticide was applied 

 and marking the area occupied by them, he counted them each day 

 thereafter for several days, and thus arrived at an exact conclusion 

 as to the effect of the fluid applications and the incidental rains. 

 Thus, on No. 1, 300 scales counted March 3 were reduced to 188 by 

 March 15 — a loss of 37 per cent. On No. 11, 400 scales were re- 

 duced in the same time to 223 — a loss of 44 per cent. Both these 

 trees, it will be remembered, were sprayed with the insecticide 

 March 3, and daily thereafter for one week with fifteen gallons of 

 water. On No. 3, 100 scales were re luced in eight days to 72— a loss 

 of 28 per cent., this tree having been three times sprayed, with 

 fifteen gallons of water each time. On No. f), sprayed once with 

 thirty gallons, the loss was 25 per cent, in eight days; and on No. 



