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 twelfth 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 w^ithin 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 IJ 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 



