450 THE GYPSY MOTH. 



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



No. 6. — March 7, 1894. Ten caterpillars, three days 

 old, were placed upon lettuce leaves which had been treated 

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

 of water. On the ninth day six were dead and four lost. 



No. 7. — 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 J- lb. to 150 gal. of 

 water. All lived through the experiment (seventeen days). 



Check experiment : none dead. 



No. 8. —May 28, 1894. Ten caterpillars, of the first 

 molt, were placed on lettuce leaves which had been treated 

 with arsenate of lead, in the projDortion of \ lb. to 150 gal. 

 of water. One died the third, one the fourth, one the 

 seventh and one the ninth day ; the remainder lived through 

 the experiment. 



Check experiment : none dead. 



No. 9. — 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. One died the fifth and two the eleventh day ; the 

 remainder lived through the experiment. 



Check experiment : none dead. 



No. 10. — June 21, 1894. Ten caterpillars, of the third 

 molt, were placed on elm leaves -ydiich had been sprayed 

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

 of water. One died the fourth, one the fifth and one the 

 sixth, two died and one pupated the seventh, two died the 

 eighth, one the tenth and one the eleventh day. 



Check experiment : one died the seventh and one the 

 ninth day ; one was lost the tenth day. 



No. 11 (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 nine fourth-molt caterpil- 

 lars placed upon it. July 31, for lack of food, they were 

 transferred to a fresh branch, which was left unsprayed. All 

 these caterpillars pupated and six emerged. Foliage unin- 

 jured. 



No. 12 (field experiment). — June 29, 1893. A branch 



