INSECTICIDES. 463 



No. 81. June 21, 1894. Ten caterpillars, of the third 

 molt, were placed on elm leaves which had been sprayed 

 with arsenate of lead, in the proportion of 3 Ibs. to 150 gal. 

 of water. Three died the fourth, five the sixth and two the 

 seventh day. 



Check experiment : one died the seventh day. 



No. 82. June 29, 1894. Ten caterpillars, of the fourth 

 molt, were placed on elm leaves which had been sprayed 

 with arsenate of lead, in the proportion of 3 Ibs. to 150 gal. 

 of water. Two died and one pupated the second day ; two 

 died the third, two the fourth and three the fifth day. 



Check experiment : two pupated the second and one the 

 fifth day. 



Xo. 83 (field experiment). June 30, 1893. A branch 

 of a small oak tree was sprayed with arsenate of lead, in the 

 proportion of 3 Ibs. to 150 gal. of water, and seven fourth- 

 molt caterpillars placed upon it. The branch was resprayed 

 July 20, on account of rain. All of these caterpillars died 

 within twenty-five days after the first spraying, and five days 

 after the second. Foliage uninjured. 



No. 84 (field experiment). June 30, 1893. A branch 

 of oak was sprayed with arsenate of lead, in the proportion 

 of 3 Ibs. to 150 gal. of water, and eight fourth-molt cater- 

 pillars placed upon it. August 27, all were dead. Foliage 

 uninjured. 



Js'o. 85. July 9, 1894. Ten caterpillars, of the fifth 

 molt, were placed on leaves which had been sprayed with 

 arsenate of lead, in the proportion of 3 Ibs. to 150 gal. of 

 water. One died and one pupated the third day; one 

 pupated the sixth day : three died the seventh day ; one died 

 and two pupated the ninth day ; and one pupated the thir- 

 teenth day. 



Check experiment : one pupated the fourth, fifth and sixth 

 days : one died the seventh day ; one pupated the eighth and 

 two the ninth day ; and one died the eleventh day. 



No. 86 (field experiment). July 9, 1894. Ten cater- 

 pillars, of the fifth molt, were placed on willow branches 

 which had been sprayed with arsenate of lead, in the propor- 

 tion of 3 Ibs. to 150 gal. of water. One died the first and 

 one the second day ; one pupated the fifth, two the sixth and 



