INSECTICIDES. 457 



No. 47 (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 pro- 

 portion of 1 lb. to 150 gal. of water. One pupated the fifth 

 and one the sixth day ; one died and one pupated the seventh 

 day ; one pupated the tw^elfth day ; one died the thirteenth, 

 one the fifteenth and one the sixteenth day ; one pupated the 

 twenty-fourth and one the twenty-eighth day. 



No. 48 (field experiment). — June 26, 1893. An apple- 

 tree branch was sprayed with arsenate of lead, in the pro- 

 portion of 1 lb. to 150 gal. of water, and eight fifth-molt 

 caterpillars placed upon it. Of these, only one died before 

 pupating, and, of those that pupated, one died without 

 emerging. Foliage uninjured. 



No. 49 (field experiment). — -June 26, 1893. An apple- 

 tree branch was sprayed with arsenate of lead, in the pro- 

 portion of 1 lb. to 150 gal. of water, and ten fifth-molt 

 caterpillars placed upon it. One of these died before pupat- 

 ing, and, of the remaining nine, eight completed the process 

 of pupation and emerged. The foliage was uninjured. 



No. 50 (field experiment). — July 1, 1893. A small oak 

 branch was sprayed with arsenate of lead, in the proportion 

 of 1 lb. to 150 gal. of water, and ten large fifth-molt cater- 

 pillars placed upon it. All died within twelve days after 

 spraying. Foliage uninjured. 



1^ lb. Arsenate of Lead to 150 gal. Water. 



No. 51. — 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 1| lbs. to 150 

 gal. of water. One died the fourth, three the fifth, one the 

 sixth and one the twelfth day ; those remaining lived 

 through the experiment. 



No. 52. — 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 1^ lbs. to 150 gal. of 

 water. Three died the fifth day ; the remainder lived through 

 the experiment and molted. 



Check experiment : none dead. 



No. 53.— May 28, 1894. Ten caterpillars, of the first 



