INSECTICIDES. 467 



day ; one pupated the third day ; two died the fourth and 

 one the fifth day. 



No. 105 (field experiment). June 21, 1893. A branch 

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

 of 5 Ibs. to 150 gal. of water, and ten fourth-molt caterpillars 

 placed upon it. July 5, the last one was dead. In this 

 experiment five or six days were required for the poison to 

 take effect ; after that time, however, the caterpillars died 

 rapidly. 



No. 106. July 9, 1894. Ten caterpillars, of the fifth 

 molt, were placed on elm leaves which had been sprayed 

 with arsenate of lead, in the proportion of 5 Ibs. to 150 gal. 

 of water. One pupated the third day ; one died the fourth 

 and one the fifth day ; one pupated and one died the sixth 

 day ; two died the seventh and one the eighth, twelfth and 

 thirteenth days. 



Check experiment : one died the third day ; one pupated 

 the fifth day ; two died the sixth and one the seventh day ; 

 one died and one pupated the eleventh day ; one pupated 

 the twelfth day. 



No. 107 (field experiment). July 9, 1894. Ten cater- 

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

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

 tion of 5 Ibs. to 150 gal. of water. One died and one 

 pupated the fourth day ; two died the eleventh and two the 

 twelfth day ; one pupated the seventeenth, one the nineteenth 

 and two the twentieth day. 



6 Ibs. Arsenate of Lead to 150 gal. Water. 



No. 108. March 7, 1894. Ten caterpillars, three days 

 old, were placed on lettuce leaves which had been treated 

 with arsenate of lead, in the proportion of 6 Ibs. to 150 gal. 

 of water. One died the first, one the second, three the third, 

 four the fourth and one the fifth day. 



No. 109. May 9, 1894. Ten caterpillars, six days old, 

 were placed on lettuce leaves which had been treated with 

 arsenate of lead, in the proportion of 6 Ibs. to 150 gal. of 

 water. Two died the first, five the third and three the fifth 

 day. 



Check experiment : none dead. 



