INSECTICIDES. 



465 



No. 93.— 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 4 lbs. to 150 gal. 

 of water. One died the third, one the fourth, two the fifth, 

 three the sixth and three the seventh day. 



Check experiment : one died the seventh day. 



No. 94. — 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 4 lbs. to 150 gal. 

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

 fourth, one the fifth and one the sixth day. 



Check experiment : one pupated and one died the second 

 day ; one pupated the third day ; and one died the fifth day. 



No. 95 (field experiment). — June 21, 1893. A branch 

 of hop-hornbeam was sprayed with arsenate of lead, in the 

 proportion of 4 lbs. to 150 gal. of water, and ten fourth-molt 

 caterpillars placed upon it. In this experiment eight of the 

 ten caterpillars died within nine days ; the other two lived 

 twelve and thirteen days longer. Foliage uninjured. 



No. 96.— 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 4 lbs. to 150 gal. 

 of water. One pupated and two died the fourth day, two 

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

 one the seventh day. 



Check experiment : one died the fourth day. 



No. 97 (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 4 lbs. to 150 gal. of water. One died and one 

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

 day ; one pupated the seventh and one the ninth day ; one 

 died the eleventh day ; one pupated the twelfth day ; one 

 died the fifteenth day ; one pupated the twenty-ninth day. 



No. 98 (field experiment). — June 21, 1893. A branch 

 of hop-hornbeam was sprayed with arsenate of lead, in the 

 proportion of 4 lbs. to 150 gal. of water, and ten fifth-molt 

 caterpillars placed upon it. July 12, all were dead. Al- 

 though these were fifth-molt caterpillars, they succumbed to 

 the poison much quicker than those of the fourth molt, six 



