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

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

 experiment fiv^e or six days were required for the poison to 

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

 rapidly. 



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

 molt, wxre placed on elm leaves w^hich had been sprayed 

 with arsenate of lead, in the proportion of 5 lbs. 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 lbs. to 150 gal. of water. One died and one 

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

 tw^elfth day ; one pupated the seventeenth, one the nineteenth 

 and two the twentieth day. 



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



No. 108.— March 7, 1894. Ten caterpillars, three da^-s 

 old, were placed on lettuce leaves which had been treated 

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

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

 day. 



Check experiment : none dead. 



