INSECTICIDES. 453 



ing, and, of the seven that pupated, four emerged. Foliage 

 uninjured. 



No. 23 (field experiment). — June 29, 1893. An oak 

 branch was sprayed with arsenate of lead, in the proportion 

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

 were placed upon it. July 20, the branch was resprayed on 

 account of rain. One died before pupating, and eight of 

 the nine that pupated emerged. Foliage uninjured. 



No. 24 (field experiment). — June 28, 1893. A branch 

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

 proportion of 2- lb. to 150 gal. of water, and nine fifth-molt 

 caterpillars placed upon it. On the 19th of July, they were 

 removed to a freshly sprayed branch. Of the eight that 

 pu[)ated, six emerged. Foliage uninjured. 



No. 25 (field experiment). — June 28, 1893. A branch 

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

 proportion of ^ lb. to 150 gal. of water, and ten fifth-molt 

 caterpillars placed upon it. July 15, as the food supply was 

 getting low, the caterpillars were removed to another branch 

 which was not sprayed. Three died before pupating, and, of 

 the seven which pupated, six emerged. Foliage uninjured. 



No. 26. — June 29, 1893. An oak branch was sprayed 

 with arsenate of lead, in the proportion of ^ lb. to 150 gal. 

 of water, and nine fifth-molt caterpillars placed upon it. 

 July 5, they were transferred to a freshly sprayed branch. 

 Only one of these caterpillars died before beginning to 

 pupate, and, of those that pupated, seven emerged. Foliage 

 uninjured. 



No. 27 (field experiment). — June 29, 1893. A branch 

 of oak was sprayed with arsenate of lead, in the proportion 

 of ^ lb. to 150 gal. of water, and ten fifth-molt caterpillars 

 placed upon it. July 15, for lack of food, they were trans- 

 ferred to a freshly sprayed branch. None of these cater- 

 pillars died before pupating, and five emerged. Foliage 

 uninjured. 



I lb. Arsenate of Lead to 150 gal. Water. 



No. 28.— 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 | lb. to 150 gal. 

 of water. On the fourth day one died, on the fifth three, on 



