INSECTICIDES. 421 



No. 8 (field experiment). June 28, 1893. A branch 

 of hop-hornbeam was sprayed with Paris green, in the pro- 

 portion of Ib. to 150 gal. of water, and six fourth-molt 

 caterpillars placed upon it. July 5, the foliage was so badly 

 burned that the caterpillars were transferred to a freshly 

 sprayed oak branch. July 19, the branch was resprayed 

 on account of heavy rains. Of the six caterpillars, only 

 two, and possibly one of these was injured, died before 

 pupating. Of the four that pupated, two emerged. The 

 foliage of the hop-hornbeam was very badly burned, while 

 that of the oak was in good condition. 



No. 9. July 10, 1894. Ten caterpillars, of the fifth 

 molt, were placed on elm leaves which had been sprayed 

 with Paris green, in the proportion of Ib. to 150 gal. of 

 water. One died the third day ; one pupated the fourth, 

 three the seventh and three the eighth day ; two died the 

 eleventh day. 



Check experiment: three pupated the fourth day; one 

 died the seventh and one the eighth day. 



No. 10 (field experiment). July 7, 1894. Ten cater- 

 pillars, of the fifth molt, were placed on willow branches 

 which had been sprayed with Paris green, in the proportion 

 of Ib. to 150 gal. of water. One died the eighth and one 

 the eleventh day ; one pupated the thirteenth day ; one died 

 and two pupated the fourteenth day ; one pupated the twen- 

 tieth, one the twenty-third, one the twenty-eighth and one 

 the twenty-ninth day. 



No. 11 (field experiment). June 28, 1893. A branch 

 of hop-hornbeam was sprayed with Paris green, in the pro- 

 portion of Ib. to 150 gal. of water, and ten caterpillars, of 

 the fifth molt, placed upon it. July 5, the foliage was so 

 badly burned that the caterpillars were transferred to a 

 freshly sprayed branch of oak. On the 15th of July, for 

 lack of food, they were again removed to another branch of 

 oak which had also been sprayed. Only one caterpillar 

 died before pupating, and that one lived twenty-four days 

 after the first spraying. Of the nine that pupated, five 

 emerged. The foliage of the hop-hornbeam was very badly 

 burned, while that of the oak was only slightly so, if at all. 



