INSECTICIDES. 469 



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

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

 tion of 6 Ibs. to 150 gal. of water. One died the second 

 day ; one pupated the third day ; two died the fifth, two the 

 sixth and one the eleventh day ; one pupated the thirteenth, 

 one the sixteenth and one the nineteenth day. 



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



No. 117. 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 7 Ibs. to 150 gal. 

 of water. Three died the first, three the second and four 

 the fifth day. 



No. 118. 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 7 Ibs. to 150 gal. of 

 water. One died the second, five the third, two the fourth, 

 one the fifth and one the seventh day. 



Check experiment : none dead. 



No. 119. May 28, 1894. Ten caterpillars, of the first 

 molt, were placed on lettuce leaves which had been treated 

 with arsenate of lead, in the proportion of 7 Ibs. to 150 gal. 

 of water. Five died the third, one the fourth, two the sixth 

 and two the seventh day. 



Check experiment : one died the fourth day. 



No. 120. June 10, 1894. Ten caterpillars, of the 

 second molt, were placed on elm leaves which had been 

 sprayed with arsenate of lead, in the proportion of 7 Ibs. to 

 150 gal. of water. One died the fourth, one the fifth, seven 

 the sixth and one the ninth day. 



Check experiment : none dead. 



No. 121. 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 7 Ibs. to 150 gal. 

 of water. One died the second, four the third, four the 

 sixth and one the seventh day. 



Check experiment : none dead. 



No. 122. June 28, 1894. Ten caterpillars, of the fourth 

 molt, were placed on elm leaves which had been sprayed 



