INSECTICIDES. 449 



No. 72 (field experiment). July 7, 1894. Ten cater- 

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

 which had been sprayed with Paris green and lime, in the 

 proportion of 6 Ibs. each to 150 gal. of water. One died 

 the fourth, one the sixth, two the seventh and one the eighth 

 day ; one pupated the fourteenth, one the fifteenth, one the 

 sixteenth and two the eighteenth day. 



Experiments with Arsenate of Lead. 

 \ lb. Arsenate of Lead to 150 gal. Water. 



No. 1. 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 | lb. to 150 gal. 

 of water. One died the fifth, one the sixth and one the 

 seventh day ; those remaining lived and molted. 



No. 2. 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 ^ lb. to 150 gal. of 

 water. One died the fifth day ; those remaining lived and 

 molted. 



Check experiment : none dead. 



No. 3. 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 lb. to 150 gal. 

 of water. All lived through the experiment. 



Check experiment : none dead. 



No. 4. June 10, 1894. Te.n caterpillars, of the second 

 molt, were placed on elm leaves which had been sprayed 

 with arsenate of lead, in the proportion of ^ lb. to 150 gal. 

 of water. All lived through the experiment. 



Check experiment : none dead. 



No. 5. 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 | lb. to 150 gal. 

 of water. One died the seventh, three the eighth and one 

 the ninth day; one pupated the tenth day; one died the 

 eleventh day. The remainder lived through the experiment. 



Check experiment : one was lost the seventh day ; one 

 pupated the eighth day ; two died the tenth day. 



