INSECTICIDES. 



449 



Xo. 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 lbs. 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 luith 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 -J 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 -J lb. to 150 gal. 

 of water. All lived through the experiment. 



Check experiment : none dead. 



No. 4. — 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 ^ 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 -J- 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. 



