INSECTICIDES. 423 



wltli Paris green, in the proportion of |. 11), to 150 gal. of 

 water. One died the second, three the third, three the fifth, 

 three the sixth and one the seventh day. 



Check experiment : one accidentally killed the seventh 

 day. 



No. 18. — June 29, 1894. Ten caterpillars, of the fourth 

 molt, were placed on elm leaves which had been sprayed 

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

 water. Two died the second, three the third, three the fifth 

 and two the sixth day. 



Check experiment : one pupated the third and one died 

 the fourth day. 



No. 19 (field experiment). — June 27, 1893. A branch 

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

 portion of 1^ lb. to 150 gal. of water, and six fourth-molt 

 caterpillars placed upon it. July 8, the foliage was so 

 l)adly burned that the leaves fell off, and the caterpillars 

 were removed to another branch which had not been sprayed. 

 By August 12, all of the caterpillars were dead, with the 

 exception of one which pupated and emerged. 



No. 20 (field experiment) . — June 27, 1893. A branch 

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

 portion of |- lb. to 150 gal. of water, and ten fourth-molt 

 caterpillars were placed upon it. July 8, one caterpillar 

 had died and the foliage had become badly l)urned. The 

 remaining caterpillars were transferred to a freshly sprayed 

 oak branch. July 19, all the caterpillars were dead. Foli- 

 age slightly burned. 



No. 21.— 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 ^ 11). to 150 gal. of 

 water. One died the second and one the third day ; two 

 died and one pupated the fourth day ; two died and one 

 pupated the sixth day ; one died the eleventh and one the 

 twelfth day. 



Check experiment : one pupated the third day ; one died 

 the fourth day ; one pupated the sixth, two the eighth, one 

 the ninth and one the eleventh day. 



No. 22 (field experiment). — July 7, 1894. Ten cater- 



