452 THE GYPSY MOTH. 



one the tenth and one the eleventh day ; the remainder lived 

 through the experiment. 



Check experiment : none dead. 



No. 18. — June 10, 1894. Ten caterpillars, of the second 

 molt, were placed on elm leaves which had been sprayed 

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

 of water. Two died the fifth, one the seventh, three the 

 eighth, two the ninth, one the tenth and one the twelfth day. 



Check experiment : none dead. 



No. 19. — 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 2- lb. to 150 gal. of 

 water. Two died the third, three the seventh, two the 

 eighth, one the tenth and two the twelfth day. 



Check experiment : two died the seventh and one the 

 eighth day ; two were lost. 



No. 20 (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 fourth-molt 

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

 having given out and two of the caterpillars having died, 

 those remaining were transferred to a freshly sprayed branch. 

 Of the ten, two died before pupating, and of the eight that 

 pupated, five emerged. Foliage uninjured. 



No. 21 (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 nine fourth- 

 molt caterpillars placed upon it, July 19, as the food supply 

 was nearly gone, the caterpillars were removed to a freshly 

 sprayed branch. One died before beginning to pupate, and 

 of the eight which pupated, six emerged. Foliage unin- 

 jured. 



No. 22 (field experiment). — June 29, 1893. A branch 

 of a small oak tree was sprayed with arsenate of lead, in the 

 proportion of ^ lb. to 150 gal. of water, and nine fourth- 

 molt caterpillars were placed upon it. July 20, they were 

 transferred to a freshly sprayed branch, both on account of 

 the food supply and rain. It was noticeable that on the old 

 branch the caterpillars had eaten all of the old, tough leaves, 

 and left the young and fresh ones. Two died before pupat- 



